Every performance agency shows the same pitch: dashboards up and to the right, a trophy case of ROAS screenshots. The screenshots are real. They are also survivorship — nobody presents the accounts that churned. Evaluation needs better instruments than the pitch deck.
1. Do they speak economics or platform?
Ask how they would judge success on your account. If the answer lives entirely inside the platform — ROAS, CTR, CPM — you are hiring a media operator. If it reaches your P&L — CAC against contribution, payback, marginal returns at higher spend — you are hiring a growth partner.
“Ask what they do when results decline. The answer is the agency.”
2. What is the creative system?
Performance accounts rarely die from bid strategy; they die from creative fatigue. Ask what they do when results decline. The answer is the agency. A real answer names a testing cadence, a volume of new concepts per week, and who produces them. A weak answer mentions “optimisations.”
3. How honest is the measurement?
Probe their relationship with attribution. Good agencies explain its limits and triangulate; weak ones quote the platform's own numbers as gospel — numbers that grade the platform's homework.
4–6: Incentives, transition, ownership
Do fees rise with spend, and if so, what keeps their scaling advice honest? What happens to your account, audiences and learnings if you part — do you own the ad accounts and data? And what will your internal team know at the end of the engagement that it didn't at the start?
The right agency makes itself progressively less mysterious. If twelve months in, you understand your growth engine no better than at the start, you rented performance. You didn't build it.
Facing this question inside your business?
Tell us the growth or commercial challenge you are working through — we will help determine where the constraint sits.