My gripe is not just restricted to Bars.
Its when you walk up to the cashier, ask for the bin, wait an inordinate amount of time for its preperation and just as they are about to get out the change, someone asks them a question or calls them and they stop serving you and begin attending to something else....
The other is of course, the blind waitresses of which there are many, you can wave furiously, call out "NONG KUP!", even expose your gentalia and shake it at her, and she will just continue to look through you, dreaming of her next plate of Som Tum I expect...