Compensated by asking for more (1500? 2000? for short time). Maybe they get paid enough to not being dependent on offs (stickman wrote that many bars in Bangkok pay their ladies so much thay don't have to go with customers, or can pick customers, or ask for crazy money).
I just (yesterday night) was in Eros, 3 drinks at 100 each, one off fee 300, total 600 THB! I know where I will take my business.