"Can you make ________ well?"
"Is your ______ as good as Starbucks?"
"How's your _______?"
They know you'll say it's good, because you really shouldn't say anything else. Even if you believe otherwise - which you shouldn't, really - the most basic business acumen dictates selling them what they want, and that means confirming quality.
Given that the answer is never really in question, and that the question itself really isn't a question, what they really want is for you to make the drink, make it well, and prove it to them. Prove that it's a great whatever, better than Starbucks, better than your nearest competition.
I love those questions - or, if we're going to name them honestly, challenges. I love the chance to make something to a specific taste, cater to the details of a "picky order", and if I'm being honest, fucking nail it.
Better than Starbucks? Easily. Better than wherever else you've come from? Chances are, yes. I had better think so. If I'm knowingly making a suboptimal product, there's a problem.
This is a matter of pride, but also, mere pragmatism. It would be lovely to think that my shop makes money because people simply cannot resist my dazzling wit and feathered bangs, but I know better. While the barista matters, and people appreciate and value the personal interaction (and the hair), the drink still has to be dialed.
It's a revelation I know: Good drinks lead to better business.
So, customers, speaking on behalf of every good barista I've ever known: Tell me your drink is hard, that you're picky, that only so and so at such and such has ever made it right. Ask me if I can do it at all, or, god forbid, better than ever. I'll smile, give a succinct confirmation that yes, I can, and yes, I will. I'll make the drink, then smile again, as you tell me how great it is. "Thanks," I'll say. "Told you," I'll think.