The dreadful pay bars in AA's Admiral Clubs are only compounded by the attitude of the bar staff if you don't proffer the expected tip on top of the cost of the drink as well. Inevitably, Miami is the worst for this. Incidentally they do not pay their bar staff (except in some cities like San Francisco where stricter minimum wage laws apply), they are expected to live off their tips.
The whole US airline attitude to drinks is surprising. Now they have gone to charging for them inflight as well. I put it down to the "bible-belt" attitudes held at their HQ's which sees any free drink as Work of the Devil.