Gay Prague is fairly up front; once you get beyond the locked doors it seems anything goes, although it also goes that various venues provide various levels of service and quality.
At most clubs in Prague you will get a 'drink ticket' - also called consumption card. Your consumption will be noted on this paper. Payment usually is when you leave the place. If you loose the ticket usually a high penalty fee is required.
It has been said that Prague resembles a European Bangkok.