I have been a regular at KP and 37D for a while, and all the staff at KP knows me by name.
When I come in and my regular picks are not available, they always start me off with pork chop. Even though they know me, they figure the old gwailo is easily satisfied with whatever Chinese chick they bring out
. This is human nature, get as many waiting guys paired up with available girls and into the rooms having sex and collect the money.
I am not shy about sending them back and asking to see another. At KP they are accustomed to this routine by me and don't seem to mind (and sometimes when I say "no thanks, bring another I keep a list of girls who I have had once before but were not worth a repeat, and I say "but don't bring me (for example) BoBo, Ching Ching or Lisa"
and they usually abide. However, when I do this at 37D they are less flexible when I send back one or two.
Regarding the waiting, I think it is simply supply and demand, when you reject what you have on offer at the moment, you simply have to wait for more chicks to become available.
I never leave a big tip, usually one $10 coin, unless I have been partoclarl;y hard to please on that day, but I do bring lai see to all the staff every year.
That's my experiences.