How to check a PPC agency's evidence

Mistake: Accepting feature claims without proof

The costliest mistake is accepting an agency's feature count without checking the evidence behind it. Unsupported claims are hard to audit and may leave you paying for a capability that does not fit your accounts. Ask which sources support each claim before scoring a PPC agency.

Set your assessment criteria before reviewing claims. Decide whether you are buying a licence, a managed service or a hybrid: your team executes under a licence, the agency takes on execution for a managed service, and a hybrid divides the work. Each model changes which evidence matters.

Check whether the proposed tool or service can handle your actual scale. A solution suited to one account in one market may not support several brands, currencies or reporting calendars, so match the shortlist to the accounts you run.

Set a minimum evidence bar by requiring the agency to name its data sources, so you can audit them later. A procurement framework can help put a pitch in context, but does not prove a supplier meets a category. Use the linked supplier categories as prompts, then ask the agency to substantiate its claims.

Mistake: Trusting summaries instead of primary sources

A vendor's summary is weaker than the platform's own documentation, so verify claimed features against primary material. TikTok's advertising help centre explains campaign setup and optimisation; use TikTok Business Centre to check related tooling claims rather than relying on the agency's description.

For search advertising, consult Google Ads Help and Microsoft Advertising Help as well. Check which release of the documentation supports each claim, because advertising interfaces change often and a screenshot from an older version does little to establish current behaviour. Ask the agency to identify its source release and compare the claim with relevant platform material.

Do not treat automation language as self-explanatory. Programmatic buying and automated bidding use overlapping vocabulary, but their mechanics are not necessarily the same. When a vendor uses automation loosely, ask for a precise explanation and check it against the neutral IAB UK reference, Back to Basics Guide to Programmatic.

Mistake: Treating a partner listing as proof of capability

A partner directory can confirm that a formal relationship exists, but it cannot show an agency's competence or suitability for your account. Use listings to identify a claimed integration, not as proof of its quality, support or performance, and ask the agency how it tests new integrations before recommending them.

Check LinkedIn's Marketing Partners directory to confirm that a named integration exists instead of relying on a second-hand description. For other platforms, consult the Google Partners directory, Microsoft Advertising Partner programme and Meta Business Partners. A listing establishes a relationship, not the value of the integration for your needs.

Mistake: Accepting measurement terms without checking their meaning

A reported conversion may use a different definition from the platform's conversion count. Before accepting a measurement claim, ask for the platform's definition of a conversion, then check whether the agency's reporting and attribution logic follow that definition.

Request an anonymised sample account audit and test a live claim against the account's Google Ads change history or Microsoft Advertising change history. Inspect the conversion-action settings and ask how the agency connects those settings to the figures in its report, rather than assuming the reported measurement matches the platform.

Mistake: Assuming the same legal check fits every campaign

Platform documentation is usually global, while legal checks depend on the campaign and data involved. For UK campaigns, identify the applicable UK rules rather than assuming that targeting England, Scotland, Wales or Northern Ireland changes the requirements. Check which UK nations the tooling and reporting actually cover.

If an agency handles personal data or client contracts, verify the legal basis for the work instead of relying on a technical claim.

Check the UK GDPR, Data Protection Act 2018 and PECR with the ICO (Information Commissioner's Office), the UK data-protection authority. Review processor terms, data access and exit arrangements, and check UK advertising claims against the Advertising Standards Authority (ASA) and the CAP Code.

Mistake: Using a scorecard whose weights you cannot explain

A weighted score can help compare evidence, but the figures below are illustrative for a mid-sized advertiser and should be adjusted to your buying model. Keep a record of why each weight was chosen, so later disagreements are easier to settle and the rubric remains stable between pitches.

Score each criterion from one to five, multiply by its weight and add the results. Judge the evidence against your chosen criteria, not just the agency's presentation, and be prepared to explain how each score reflects the documentation, fit and commercial terms you have checked.

Do not let a strong commercial score cancel out weak source transparency. If an agency scores well on fees and exit terms but poorly on evidence for its claims, treat the result as a negotiation risk rather than a bargain. First compare evidence against your criteria, then compare price among the shortlisted options.

Partner directories confirm formal relationships, not quality, fit or support standards, so use them only to identify a partner. Data protection and advertising rules generally apply across the UK, although some duties and reporting expectations differ in Scotland, Wales and Northern Ireland. Check the position for each nation you target.

Review the rubric at each annual planning cycle, or sooner if your buying model changes; platform documentation and partner listings can move quickly. Add any criterion that caused a dispute after the pitch, so the next comparison reflects the evidence gaps you encountered rather than repeating them.

Mistake: Leaving verification questions until the pitch is over

Verbal assurances are difficult to compare with delivery later, so put checks in writing before choosing an agency and keep its replies as a record. Ask for documentation supporting each claimed feature, including a link, and establish who owns the advertising account and conversion data if the relationship ends.

Ask what happens to historical performance data on exit, how quickly the agency will flag a platform change affecting your account, and who will tell you. Get the escalation route for a performance drop, and ask how the agency tests new integrations before recommending them.