How to read an agency case study without being fooled
Every trades marketing agency with a website has a case study, and every case study has a big number. Some of those numbers are real, some are real but irrelevant, and some are carefully worded to mean less than they appear to. This guide sets out how a sceptical reader takes one apart in ten minutes.
Start with what is not on the page
A case study is a document produced by the seller, about the seller, for the purpose of selling. That does not make it false. It does mean the omissions tell you as much as the inclusions.
Before reading the results, scan for four things: a named client, a timeframe, the starting point, and the budget. A case study that has all four can be checked. One that has none of them is an advert with a chart in it.
Of the thirty-odd UK trades agencies we track, roughly half publish case studies. A fair number are anonymised, described as 'a roofing company in the North West' or similar. Anonymity is sometimes at the client's request, but it removes your ability to phone the business and ask.
Check one: the missing denominator
'Leads up 300 per cent' is the most common trades marketing headline and the least informative. Three hundred per cent of what? If the business had two enquiries a month and now has eight, that is a 300 per cent rise. It is also six extra phone calls.
Look for absolute numbers alongside percentages. If an agency gives only the percentage, it has usually chosen to, because the absolute figure is less impressive.
Check two: leads, quotes or jobs?
A lead is a form filled in or a phone that rang. A quote is a lead that turned into a site visit and a price. A job is money. Agencies report the first because it is the one they control; the tradesperson cares about the third.
The gap between them can be enormous. In a worked example, 40 Facebook leads at £25 each cost £1,000. If a quarter become quotes and a third of quotes become jobs, that is three jobs, at £333 of ad spend each before the agency fee. Whether that is good depends entirely on whether the jobs are £400 gutter repairs or £8,000 re-roofs. A case study that stops at 'leads' has stopped before the part that matters. Our explainer on what agencies mean by a qualified lead goes further on the definitions.
Check three: the vanishing timeframe
Results over what period? 'Generated 150 leads' means something different over one month and over eighteen. Some case studies give a start date and no end date, some quote a single remarkable month, and some are silent.
Also ask when the case study was written. A campaign that worked in 2021, when Facebook lead costs were lower, is weaker evidence for 2026 than it looks.
Check four: the starting point
Taking a business from no website to page one of Google for its own name is easy and looks dramatic. Taking an established firm from position eight to position two for 'roofers Leeds' is hard and looks modest. The before matters as much as the after.
Ranking case studies, which several agencies favour, are especially prone to this. Before-and-after screenshots of map pack positions rarely say which keyword, which town, or how many searches that keyword actually gets.
Check five: who else was working on it?
Revenue results are the gold standard, but revenue has many parents. A kitchen company that doubled turnover while an agency ran its marketing may also have hired two salespeople, opened a showroom and raised prices. Honest case studies acknowledge this. Most do not mention it.
The question to ask the agency directly is: how did you attribute this to your work rather than to everything else the client did that year?
Check six: is it your trade and your scale?
A result for a kitchen showroom with a sales team tells a one-van plasterer very little. The channel, the budget and the sales cycle are all different. Likewise, a result in London does not transfer cleanly to a market town.
Match the case study to your situation on three dimensions: trade, business size and area type. If an agency only has case studies from a different trade, it may still be competent, but it has not shown you evidence for your business. The specialist single-trade agencies tend to score better here, for obvious reasons.
Check seven: can you verify any of it?
With a named client, you can do three things. Search the business name and town and see whether it ranks. Look at its reviews and whether they match the period of the case study. And phone them. Most tradespeople are happy to tell another tradesperson whether an agency was worth the money.
Video testimonials are better than text quotes because they are harder to fabricate, but they are still selected. One happy carpet cleaner does not tell you about the four who left.
Check eight: the survivor problem
Case studies are written about the clients who stayed and did well. Nobody publishes a case study titled 'the roofer who spent £3,000 and got nothing'. So even a shelf of genuine, verifiable case studies describes the top of the distribution, not the average.
The counterweight is churn. Ask an agency how many clients it took on last year and how many are still with it. A straight answer to that is worth more than any case study. Our piece on why tradespeople switch agencies gathers what the agencies themselves say about it.
Check nine: the language
Certain phrases should slow you down. 'Up to' means the maximum, not the typical. 'Potential' means it has not happened. 'Generated over £X in pipeline' means quotes sent, not jobs won. 'Helped' means the agency was present while something happened.
None of these are lies. They are the words of a writer who knows the precise claim would be smaller.
| Phrase | What it usually means | Ask instead |
|---|---|---|
| Leads up 300% | Small base, no absolute figure | From how many to how many, per month? |
| Up to 50 leads a month | The best month | What was the average over the contract? |
| £200k in pipeline | Quotes issued, not won | How many jobs were booked and at what value? |
| Page one rankings | For some keyword, somewhere | Which keywords, which town, what search volume? |
| Helped grow revenue | Was present during growth | How did you separate your effect from other changes? |
A ten-minute routine
Read the case study once for the story. Read it a second time with the table above beside you, writing down every figure and what it is a figure of. Then write down the five things you would need to know to be convinced, and ask the agency for them. How it responds is the real case study.
A good agency will answer most of them and admit the rest. A poor one will send you another case study.
- Named client, or a reason it is anonymous
- Absolute numbers, not only percentages
- Leads, quotes and jobs separated
- Start date, end date and starting position
- Budget and fee alongside the results
- A phone number for the client
Frequently asked questions
Are anonymised case studies worthless?
Not worthless, but unverifiable. They show the agency can describe a campaign; they do not let you check it happened. Ask for a named reference alongside.
What is the single most important number in a trades case study?
Cost per booked job, including the agency fee. Everything upstream of that, clicks, leads and rankings, is a step towards it rather than the result.
Should I ignore ranking screenshots?
Treat them as partial evidence. They show movement in Google but not which keyword, how many people search it, or whether enquiries followed.
How many case studies should an agency have?
Quantity matters less than relevance. One verifiable case study in your trade and at your scale beats ten from different industries.