How to Check E-Commerce Ad Agency Portfolios and Results: The Complete Audit Framework

If you run an e-commerce brand, you have likely received dozens of cold pitches featuring gleaming case studies. PDF decks boasting 10x Return On Ad Spend (ROAS), screenshots of Shopify dashboards showing hundreds of thousands of pounds in revenue, and client logos plastered across agency landing pages have become standard practice. Yet, when founders hire these agencies, performance frequently collapses within the first sixty days.

The reality of paid advertising across Meta, Google Ads, TikTok, and Pinterest is that agency portfolios are often crafted to showcase exceptional moments rather than sustainable unit economics. A screenshot showing a 1,000% ROAS sounds brilliant on paper, but it means virtually nothing if the campaign only spent £50 on retargeting existing brand search traffic over a weekend. Evaluating whether an e-commerce advertising partner can deliver profitable growth requires looking far past polished marketing materials.

In this guide, we break down the exact methods needed to dissect an e-commerce ad agency portfolio, audit historical performance claims, and verify whether reported results translate into actual bottom-line profit for your store.

The Anatomy of a Flawed Portfolio (What Agencies Hide)

When reviewing agency case studies, the primary challenge is separating genuine customer acquisition from inflated reporting tactics. Ad platforms offer numerous ways to present performance data that looks extraordinary to an untrained eye while hiding underlying inefficiencies.

The most common tactic involves blending branded search or heavy retargeting data with cold traffic campaigns. An agency running Google Ads might spend 80% of your budget targeting people who already typed your exact brand name into the search bar. Because these users were going to buy anyway, the campaign reports a massive ROAS. When combined with cold traffic Meta campaigns in a single portfolio slide, the overall metrics appear highly profitable, masking the fact that cold prospecting is operating at a heavy loss.

Another frequent issue is attribution window manipulation. By default, platforms often report sales based on a 7-day click or 1-day view window. If an agency opts into view-through attribution without informing you, Meta will claim credit for purchases made by anyone who simply scrolled past an ad on their feed without ever clicking it. This artificially inflates reported revenue without adding a single new customer to your database.

To evaluate portfolios accurately, you must understand the difference between platform ROAS and blended metrics like Marketing Efficiency Ratio (MER). MER calculates total revenue divided by total ad spend. When auditing an agency, ask them how campaigns impacted store-wide MER rather than relying solely on in-platform screenshots.

If you want to understand how verified data aligns with real-world business profit, take a look at our e-commerce ad agency portfolio verification guide which details exact verification steps.

Forensic Case Study Verification: How to Spot Manipulated Data

Static screenshots in slides or blog posts can easily be altered or presented without necessary context. A screenshot showing £100,000 in monthly sales looks impressive, but if the client spent £110,000 on ads to generate that revenue, the store lost substantial money. Here is how to conduct a forensic review of any case study an agency presents to you:

First, inspect the scale of ad spend. Driving a 10x ROAS on a £500 monthly budget is relatively straightforward because the ad platform only picks off the absolute easiest conversions. Replicating that efficiency at £20,000 or £50,000 per month is fundamentally different. As spend increases, audience saturation occurs, and cost per acquisition (CPA) naturally rises. In our experience running campaigns across diverse niches, maintaining efficiency while scaling budget is the true test of media buying capability.

For example, in one of our past campaigns for an outdoor equipment e-commerce store, we constructed a campaign structure designed to drive over 18,000 qualified website visitors while keeping costs strictly controlled. In another instance working with a subscription box client, we achieved a 1000% Return On Ad Spend by focusing strictly on scalable unit economics rather than artificially inflating metrics with retargeting overlap. Similarly, for a women's apparel brand, we generated a 691% return across Meta and Pinterest ads by building distinct creative angles for prospecting versus retargeting.

Second, scrutinise timeframes. Agencies frequently present case studies built around seasonal spikes such as Black Friday Cyber Monday (BFCM) or Q4 holiday shopping. A campaign that achieved a 6x ROAS during late November might struggle to reach a 1.5x ROAS in mid-February. Ask the agency to show continuous, month-over-month performance data spanning at least six to twelve consecutive months to verify stability across off-peak periods.

Third, examine product niche alignment. Scaling a high-ticket luxury item requiring a 90-day consideration cycle involves vastly different strategies than selling impulse-buy cleaning supplies. For instance, in our work with a cleaning products e-commerce brand, we delivered a 633% return and a 190% increase in revenue by focusing heavily on fast-converting video ad formats and landing page conversion rate optimisation. Make sure the agency portfolio features brands with similar price points, Average Order Values (AOV), and customer purchase frequencies as your own store.

The Reference Call Trap: How to Audit Past Clients

Asking an agency for client references seems like a logical verification step. However, standard reference calls are often structured traps. No agency will ever put you in touch with an unhappy former client. They will direct you straight to their warmest relationship—often a client who happens to be a personal friend or someone receiving discounted management fees in exchange for glowing testimonials.

In fact, from our perspective as paid advertising experts, if a prospective client asks us to call past references after reviewing detailed case studies, video breakdowns, and receiving a full account review, it signals a fundamental lack of trust that often makes working together difficult. However, if you are conducting due diligence on an unknown agency, you must skip generic questions like "Are you happy with their service?" and instead ask specific, forensic questions.

Here are seven direct questions to ask during a reference call:

• What exact breakdown of ad spend was allocated to cold prospecting versus retargeting? (Tests whether the client actually understood campaign mechanics).
• How did your overall store profitability (MER) change after hiring the agency compared to your in-platform ROAS? (Uncovers attribution inflation).
• Did the agency handle landing page design, copywriting, and creative production, or did they only manage bidding inside Ads Manager? (Evaluates true full-funnel capability).
• How did the agency handle performance dips when ad fatigue hit or ad accounts faced policy disruptions? (Reveals problem-solving capacity).
• What was their communication structure during weekly updates, and did they proactively flag declining margins? (Measures transparency).
• Did the agency push you to test new angles and product offers, or did they rely entirely on existing assets you provided? (Assesses strategic initiative).
• If you stopped working with them, what was the exact reason for the split? (Highlights underlying friction points).

By shifting the conversation toward unit economics and operational workflow, you quickly uncover whether the reference represents genuine business growth or merely a friendly favor for the agency sales team. For broader context on agency financial structures, read our guide on UK paid ads ROI guidelines for actual profit.

Demanding Live Account Access: The Ultimate Verification Framework

The single most reliable way to verify an e-commerce ad agency portfolio is to request a live, screen-shared walkthrough of an active or historical ad account (with sensitive client branding obfuscated if necessary). Never rely on pre-recorded slide decks or static screenshots.

During a live walkthrough, observe how the account was actually constructed and managed. Pay specific attention to the change log history. If an account has fewer than three to five changes logged per week during a scaling phase, the agency is likely operating on auto-pilot while charging you a hefty monthly retainer.

When auditing live account structures, verify the following setup components:

1. Audience Segmentation: Are cold prospecting audiences clearly separated from retargeting and existing customer lists? If the agency dumps all targeting into broad Advantage+ campaigns without exclusions, they may be paying to target existing buyers over and over again.

2. Creative Testing Velocity: How many distinct ad concepts (not just minor copy tweaks) are launched each month? High-performing accounts require continuous testing of new hook angles, video formats, and static visual concepts. In our experience, creative fatigue is the main reason why campaign performance degrades over time.

3. Bidding and Budget Distribution: Does the agency know when to use Cost Cap / Bid Cap strategies versus Lowest Cost / Max Conversion bidding? Cap strategies protect margins during scaling, whereas automated bidding without controls can rapidly burn through budget when auction costs rise.

For more detailed technical evaluation strategies, check out our insights on London ad experts guide to scaling spend.

E-Commerce Unit Economics & Agency MER Calculation

An agency portfolio can report stellar figures while bringing your business closer to insolvency if their team lacks a firm understanding of unit economics. Before hiring an agency, you must establish your store's break-even metrics so you can evaluate their portfolio through the lens of your business's financial reality.

To calculate your break-even ROAS, use the following formula:

Break-Even ROAS = 1 / Gross Margin %

If your e-commerce store sells products at an 80% gross margin (0.80), your break-even ROAS is 1 / 0.80 = 1.25x. Any ad spend that achieves an in-platform ROAS above 1.25x generates gross profit. However, if your gross margin is only 40% (0.40), your break-even ROAS jumps to 1 / 0.40 = 2.5x. An agency portfolio showing a 2.0x ROAS would be highly profitable for the first store, but catastrophic for the second.

When reviewing portfolio case studies, check whether the agency included management fees in net ROI calculations. An agency generating £50,000 in revenue from £20,000 in ad spend on a 50% margin store yields £25,000 in gross profit—leaving £5,000 net profit. But if the agency charges a £4,000 monthly retainer, actual profit collapses to £1,000. True growth partners evaluate campaign performance inclusive of all software, creative, and management costs.

To explore financial modeling and agency fee structures, consult our user acquisition agency pricing blueprint.

Evaluating Creative Capability & Full-Funnel Ownership

A major flaw in traditional e-commerce ad agencies is a hyper-fixation on media buying settings inside Ads Manager while ignoring the landing page experience. In modern paid advertising, media buying algorithms (like Meta's Andromeda or Google's PMax) handle targeting automation exceptionally well. The primary lever for performance optimization has shifted to creative assets and landing page conversion rates.

If an agency portfolio consists only of target settings, audience interest lists, and bidding strategies, they are relying on outdated methodology. A true expert paid advertising partner must demonstrate competence across the entire conversion funnel.

When reviewing portfolio assets, evaluate agency creative output against these core criteria:

1. Direct Response Copywriting: Does the ad copy focus on solving customer pain points, highlighting clear benefits, and removing purchase friction? Or does it rely on generic fluff like "Shop our new collection today"? Effective ads speak to urgent problems and offer tangible solutions.

2. Visual Diversity: Does the portfolio show multiple visual styles—User Generated Content (UGC) videos, high-production product videos, side-by-side comparison graphics, press quote cards, and unboxing clips? Relying on a single visual style creates quick fatigue.

3. Landing Page & CRO Integration: Does the agency build custom landing pages or direct ad traffic straight to generic homepages? Sending paid cold traffic to a cluttered homepage is one of the fastest ways to burn ad spend. In our own client work, optimizing destination pages with dedicated sales copy, customer reviews, and streamlined checkout options frequently doubles conversion rates without increasing ad spend.

For a detailed breakdown of full-funnel paid advertising strategies, read our UK paid advertising guide.

Red Flags That Should Make You Walk Away Immediately

During your initial consultation and portfolio audit, certain behaviors and claims should prompt immediate concern. Here are major red flags indicating an agency may not be able to back up claims:

• Guaranteed ROAS Metrics: No legitimate advertising expert can guarantee a specific ROAS because ad auctions, competitor bids, product demand, and supply chain factors vary daily. Anyone offering guaranteed returns is usually hiding caveats in contract fine print.
• Refusal to Share Live Account Audits: If an agency claims privacy reasons prevent them from doing a blurred live walkthrough or showing redacted campaign histories, they are likely trying to hide poor performance.
• Long-Term Lock-in Contracts Without Performance Milestones: Beware of agencies demanding 6 to 12-month non-cancellable contracts upfront. Highly competent partners usually operate on shorter commitment terms or include clear exit clauses if agreed targets are not met.
• Over-Reliance on PMax or Broad Retargeting: If an agency's sole strategy on Google Ads is running fully automated Performance Max campaigns without negative keyword lists or brand exclusions, they are likely taking credit for organic sales your brand would have generated anyway.
• Vanity Metric Focus: If an agency continually shifts conversation toward impressions, reach, click-through rates (CTR), or video views rather than Cost Per Acquisition (CPA), Return On Ad Spend (ROAS), and Net Revenue, they are avoiding financial accountability.

If you are launching a new product line or scaling into new regions, examine our London go-to-market founder blueprint for clear positioning advice.

The Step-by-Step Agency Vetting Process

To ensure you hire a partner capable of scaling your e-commerce brand profitably, follow this systematic four-step vetting workflow before signing any contract:

Step 1: Initial Portfolio & Strategy Screening
Review published case studies and look for verified client results in your specific niche or price tier. Ask clarifying questions about spend scale, seasonality, and exact campaign objectives.

Step 2: Technical & Account Strategy Review
Request a live 30-minute consultation where the agency audits your current account structure or walks through a redacted live account they manage. Evaluate creative production pipeline, testing methodology, and CRO knowledge.

Step 3: Forensic Unit Economic Alignment
Provide the agency with your store's exact profit margins, AOV, and customer lifetime value (LTV). Ask them to calculate your required break-even ROAS and propose a realistic scaling roadmap based on those numbers.

Step 4: Contract & Scope Verification
Ensure the agreement explicitly defines deliverables for creative production, copy updates, landing page builds, and reporting frequency. Verify that you retain 100% ownership of all ad accounts, pixels, and creative assets built during the contract.

For more advice on scaling your business effectively, check our strategic framework on scaling marketing to reach wider audiences.

I have detailed my main recommendations for you below:

Why Professional Guidance Makes the Difference

Choosing an e-commerce advertising partner is one of the most critical decisions an online store founder can make. Hiring the wrong agency leads not only to wasted ad spend, but also to lost market share, damaged brand equity, and months of stalled momentum.

Navigating ad platforms, conversion rate optimisation, creative production, and complex attribution modelling requires deep, hands-on experience across multiple verticals. Rather than taking agency portfolios at face value, evaluating potential partners through a structured, data-backed audit framework protects profits and ensures ad budgets drive real business expansion.

If you are unsure whether your current campaigns are performing at full potential or want an objective, expert review of your paid ad strategy, consider booking a free initial consultation with our team. We audit account structure, review unit economics, and provide clear recommendations on how to scale your store profitably.