I have not encountered any lineups per say.Almost everytime I go in to an establishment I have frequented, If I do not like the girl that brings me back / is assigned to me, I ask who is working. Everytime they will bring back one girl sometimes 2 or 3. Just have to do it in a subtle way. I am sure they have no problem with you asking can I see who is available?
I have even walked back with a RA I had been with before and asked if anyone else is working. She will bring back a girl and I will choose. No one has ever taken offense to this in front of my face.
It never hurts to ask. What are they going to do call the police or beat you down, or ban you? Remember, your the one who is paying.