I've punted there a few times and never felt ripped off, though they can be keen to cut the time short.
I always ask them at the door before going in what the deal is. As well as reduce the chance of them ripping you off, it also means you can see them up close, and it's amazing how many girls look not-quite-so-stunning when you see them much closer. Standard is 50 Euro for suck AND fuck, apparently for 20 mins. I also ask them there if they'll take their top off, as some don't if you don't ask them. If I don't like the vibe or the girl, I will politely decline, and move on. Never been a problem. If you want this or a particular position, then I'd discuss that at the door. I also aim for girls who look a bit more enthusiastic, rather than the 10s sitting on their phones looking miserable.