Although I'm not sure it would qualify as a "customer service" problem, one thing that does bother me in a bar is if the seating is uncomfortable. If nothing else, at least make it comfortable enough for me to sit around for a while. How hard can it be to find reasonably comfortable seats?
Otherwise, it can be annoying if some girl attaches herself to you the minute you walk in the door, asking for a lady drink. And if three of her friends also show up wanting drinks, then what? Rather than deal with all that, it's often easier just to get up and go to another bar. I't not that I'm a Cheap Charlie, but buying three or four or five drinks at a time can get expensive.
On the other hand, I don't really like to go into a bar and feel that I'm invisible. I guess there's a happy medium somewhere.
Don't ignore me, but don't make me put up with three or four girls, all wanting drinks 30 seconds after I walk in the door.
Rex