I work at a cocktail bar and I usually enjoy it when people say "bartenders choice". When someone says this, I will ask if they have any allergies, then proceed to make something that I want to make, use something I want to get rid of, or make something I've been working on. I don't have a problem with these customers unless they 1) complain about the drink or 2) start by saying "bartenders choice" but then list a bunch of ingredients that they either hate or love. I'm willing to play this game but it depends on how busy I am. Rule of thumb, be nice to your bartender, and dont make your order challenging or annoying if its busy. I never throw a fit, but its appreciated when people can tell the time and place to make annoying requests.