The right questions during an agency vetting process will tell you more than any case study or sales presentation ever could. If you’re running an ecommerce brand at £1M or more in revenue and evaluating potential agency partners, the questions you ask, and the answers you accept, will determine whether you end up with a growth partner or an expensive monthly expense that goes nowhere.
This framework covers the specific questions experienced ecommerce operators should be asking, organised by what each answer actually reveals about the agency.
Questions About How They Think About Profitability
Most agency pitches focus on what they’ll do: run Meta campaigns, optimise Google Shopping, build creative assets. That’s table stakes. The questions that matter are about how they think.
“How do you define a successful month for a client like us?”
Listen carefully here. If the answer centres entirely on platform-level ROAS or revenue growth, the agency is thinking about ad performance in isolation. A strong answer will reference contribution margin, blended MER, or CAC payback period. They should be talking about whether you actually made money after accounting for COGS, shipping, returns, and ad spend.
“What information do you need from us before you can build a strategy?”
An agency that jumps straight into campaign tactics without understanding your gross margins, average order value, customer lifetime value, and repeat purchase rate is building on sand. The best agencies will ask for access to your Shopify analytics, your P&L, and your historical ad account data before they even begin proposing a plan. If they’re ready to pitch you a strategy on the first call, they’re selling a template, not a tailored approach.
“How do you handle months where performance dips?”
Every brand has bad months. Seasonality, creative fatigue, algorithm changes, competitor activity, inventory issues. The question isn’t whether it will happen, it’s how the agency responds. You want to hear about a structured diagnostic process: checking creative performance, audience saturation, landing page conversion rates, and external factors. You don’t want to hear “we’ll increase spend” or “the algorithm is adjusting.”
Questions About Creative Strategy
Creative is the single most important variable in paid media performance for ecommerce brands. According to Statista’s 2025 ecommerce data, the average conversion rate across ecommerce sites sits below 2%, which means the vast majority of people who see your ads and visit your site don’t buy. Creative quality determines whether you attract the right audience in the first place and whether they convert once they arrive.
“How many new creative assets do you produce per month, and what does your testing process look like?”
For brands spending £30K or more on Meta, you should expect a minimum of 15-20 new creative variations per month. That includes a mix of formats: UGC-style video, static images, carousels, and potentially long-form video. Beyond volume, ask about their testing framework. Do they test hooks, body copy, and calls to action independently? Do they have a clear process for promoting winners and killing underperformers?
“Who produces the creative? Is it in-house or outsourced?”
There’s no single right answer here, but you need to understand the workflow. An agency with in-house creative teams can typically iterate faster than one that outsources everything. If they do use external creators (which is perfectly valid for UGC), ask how they brief those creators and how quickly they can turn around new assets.
“Can you show me a creative testing log from an existing client?”
This is a revealing ask. Agencies that take creative seriously will have detailed records of what they tested, what worked, what didn’t, and what they learned. If they can’t produce something like this, creative testing is probably ad hoc rather than systematic.
Questions About Measurement and Attribution
Attribution in ecommerce is messy. Meta over-reports. Google claims credit for everything. If an agency only shows you in-platform numbers, you’re getting an optimistic view of reality.
“How do you measure performance beyond platform-reported ROAS?”
You want to hear about blended metrics: MER (total revenue divided by total ad spend), new customer ROAS, and ideally some form of incrementality testing or post-purchase surveys. An ecommerce marketing agency that relies solely on Meta Ads Manager or Google Ads reporting to make decisions is working with incomplete data.
“Do you use any third-party attribution tools, and if so, which ones?”
Triple Whale, Northbeam, Rockerbox, and similar tools have become standard in serious ecommerce media buying. They’re not perfect, but they provide a more balanced view than platform-native reporting. If the agency doesn’t use any of these and can’t explain their attribution methodology, that’s a concern at higher spend levels.
“How do you handle the gap between what Meta reports and what Shopify shows?”
This is a practical question that reveals operational competence. There’s always a discrepancy between platform-reported revenue and actual Shopify revenue. Strong agencies have a process for reconciling these numbers and making decisions based on the most accurate data available rather than whichever number looks best.
Questions About Account Structure and Ownership
This is where commercial terms meet practical reality.
“Who owns the ad accounts?”
You should always own your own ad accounts. If an agency runs ads through their accounts, you lose all historical data, pixel learning, and audience assets when the relationship ends. Any reputable agency will insist on working within your accounts.
“What happens to our campaigns if we part ways?”
This ties into ownership. Ask specifically about transition processes. Will they hand over documentation of what’s running, what’s been tested, and what the current strategy is? Or will you inherit a black box? The answer tells you a lot about how the agency views the relationship.
“Who specifically will work on our account, and how many other accounts do they manage?”
You’re not hiring a logo. You’re hiring the people who will actually touch your ad account every day. Ask to meet them during the sales process. Ask how many accounts each team member manages. If your media buyer is juggling 15 accounts, don’t expect much proactive strategic thinking on yours.
Questions About Contracts and Fees
“What’s your minimum commitment, and what are the notice terms?”
A 3-month initial commitment is reasonable because it takes time to properly audit, rebuild, and test. After that, 30-day rolling terms are fair. Agencies that require 12-month contracts with 90-day notice periods are prioritising their own cash flow over your flexibility. That doesn’t automatically make them bad, but it does mean they’re not confident enough in their retention to let results speak.
“How is your fee structured, and does it change as our spend scales?”
Understand whether you’re paying a flat retainer, a percentage of ad spend, or a hybrid. Each model has trade-offs. A percentage-of-spend model means the agency earns more when you spend more, which can create a misaligned incentive to increase budgets regardless of profitability. A flat retainer provides predictability but may not scale well if your needs grow significantly.
“Are there any additional costs beyond the retainer?”
Some agencies charge separately for creative production, landing page builds, or strategic audits. Get this in writing upfront. Surprise invoices three months in create friction and erode trust.
The Meta-Question: How Do They Handle This Conversation?
Beyond the specific answers, pay attention to how the agency responds to being questioned thoroughly. A good marketing agency will welcome hard questions because they’ve heard them before from sophisticated clients. They’ll have clear, specific answers rather than vague reassurances.
An agency that gets defensive, rushes you toward a contract, or avoids specifics is showing you exactly how they’ll communicate once you’re a client. The vetting process is the relationship at its best behaviour. If the communication isn’t sharp now, it won’t improve after you’ve signed.
