First off, Hello, my name is Nat and I am new to eGullet. That being said, I don't think that blind testing a bartender is necessarily the right approach. I do think that there are a couple of better approaches. If you want to know if someone is at least serious about cocktails you can ask a couple of feeler questions, like if they use fresh juice, what kind of vermouth they have, ask if they have orange bitters. If they are serious about cocktails they would probably glean that you are too, rather than the usual clientele who ask what kind of vodka they have. Another thing to try is to ask their name, then no matter what they say, tell them that you heard that they make a great manhattan. This is lible to get their best effort, and when they go astray, instead of just chalking it up to a bad bar experience, tell them it was good, but next time... To me, it seems that this kind of engagement with a bartender might turn on a so-so tender to want to become good, and instead of having only a few high end cocktail bars in your city, you can start getting a few around at other places, instead of just deciding to order beer there. -Nat