Hi Phil
I think that most of the BM's here are quite shocked by what has happened in Phuket, Patong and Khao Lak. After you have been to LOS a couple of times you will realise that you make very good friends with the Bar Girls and their colleagues and although you pay for play it does not really feel like that.
Nevertheless, since you ask the question, I will answer it. The Bar Girl scene in Patong is based on a monetary transaction. Typically, if you meet a girl in a bar and you hit it off then you must pay the bar manager a "fine", usually about THB 200 and then you pay the girl directly "by arrangement". The price depends on you and the girl but historically THB 1,000 sees you through the night and THB 500 will give you a short time experience.
Within the Bar scene you have the Go-Go bars where the girls dance around poles. Sometimes the girls wear numbers and again if you meet a girl you like then you pay a fine - typically THB 500, and an arrangement with the girl usually THB 1500 or THB 2000 depending on how she feels about you. If she says THB 3000 or above then you are probably not her type.
Outside of the Bar scene you have the bigger establishments like Christins. These are brothels in the true sense. You go with the girl inside the establishment and do not take her away.
Sometimes the girls are not directly connected to the bars or are working on their own after hours. These are called Freelancers. The advice of this board is to be cautious of freelancers, particularly when you are drunk as they can take advaneforum.xxxe of you and you have little recourse in Thailand. If you abuse a Bar Girl or mistreat her in anyway then you will face the wrath of the Tourist police, not nice, or her friends, even worse.
The Thai character is to be respectful, kind and obliging. The girls are usually quite deferential and want to take care. They want to be your girlfriend and expect you to behave accordingly. Yes you do pay, Phil, but once you are there you will understand it more clearly.
I hope this is helpful
Mac