Order the flight. Rank it. Ask which one actually sells.

Find a counter that does a flight — beer taps, espresso, gelato, hot sauce, whatever they'll line up in fours — and order the whole thing. Taste in order and lock your podium before you talk to anyone. Then ask whoever's pouring which one actually outsells the rest, and make them tell you why. Your winner and the till's almost never match — the gap is the whole point.