Another term for this occupation is “B-Girl”. It works pretty much as Badtz Maru described.
I’ve known a few girls who did this. In their case, the bar paid them nothing up front. They worked on a percentage of how much a “sucker” spent.
It usually works like this: Lonely guy comes into the club for “just one drink”. The B-girl engages him in conversation and induces him to stay longer, buy more drinks, and buy her drinks also. The b-girl will order a drink of the correct color, and she is served tea instead. Of course, the guy pays for a real drink.
When the guy finally leaves the bar, the girl is paid whatever percentage was agreed upon beforehand.
This is an old con-game, but it still works a surprising amount of times.