TL;DR:
- Most agency vetting focuses on surface-level criteria that don’t predict real results.
- The best question to ask first is about the agency’s average client engagement length. This reveals whether they build partnerships or churn clients.
- Look for proof and transparency through references and relevant success stories.
- Prioritize agencies that understand your business situation, not just your industry.
- In today’s buyer-led B2B landscape, you need a long-term partner shaping demand, not just executing tasks.
Most prospect conversations we have start the same way. The CEO or CMO shows up with their vetting list ready to go: certifications, tools, team size, reporting cadence, platform expertise, and cost.
All fair questions. None of them actually tells you whether an agency can deliver for you.
If you’re evaluating agencies right now, here are the three I’d push you to ask. They’re the ones we’d want you to ask us.
1. What’s your average length of engagement?
This is the one that matters most… and almost nobody leads with it.
Industry average for an agency-client relationship is around 3.2 years, and retainer engagements average closer to 5 years (thank you, Focus Digital). For context, Syrup’s average is 4+ years with a 91% client retention rate.
Why does that number matter so much? Because marketing is compounding work. Strategy takes months to build, and results take longer. If an agency’s average engagement is 7 months, that’s a revolving door, not a partnership. You’ll feel it in the work (and eventually in your P&L).
Ask this one first. The answer tells you what kind of relationship you’re actually signing up for.
2. Do you have references?
This is the question most people do ask. It’s the safe one.
What you really want to notice is how they answer it. A good agency offers references proactively. They don’t make you chase them, and they don’t stall or generalize.
Hesitation here is an answer on its own.
3. Can you show me a success story from a client in a similar situation to ours?
Read that carefully. Similar situation, not same category.
Most people ask, “Have you worked with a [insert industry] company before?” Category experience has its place. But it doesn’t tell you enough.
What you actually need to know is whether they’ve helped a company that looks like you at the stage you’re at. A founder-led business trying to professionalize marketing. A CMO inheriting a scattered go-to-market engine. A mid-market company whose buyers have just changed on them.
Same category, different situation? That agency might still miss. Different category, same situation? That agency has probably already solved your problem (or at least learned enough to help navigate yours).
Category might be what you are asking. Situation is what you need.
Why these questions matter more right now
By now, you’ve probably heard us (and many others) talk about how buying has changed in B2B. Gartner research shows 75% of B2B buyers now prefer a rep-free buying experience, and according to 6sense research, buyers are typically 70% of the way through their decision before they ever reach out to a vendor.
Which means your agency’s job has expanded. They’re shaping how you show up in rooms you’re not invited into: in AI search results, in peer conversations, in comparison docs your prospect is building without you.
That’s a different kind of partnership, right? It takes time, trust, and an agency that’s in it for the long haul. The questions above are how you find that partner. If you want our full take on what modern B2B marketing looks like, it lives here.
