Negotiate before in the back

I was out with friends nearby, and wasn't ready to go home, so I decided to check this place out. I hadn't ever been here before. I was a little concerned about the reputation for smokiness (I'm a married nonsmoker) but it wasn't horrible. I just tried not to sit next to someone puffing away.

I sat at the bar and was approached by a fairly unattractive dancer who asked me immediately if I wanted a dance. I was two sips into my beer so I declined and said I wanted to settle in for a bit. I observed nearly every dancer who wasn't on stage at that moment paired up with who appeared to be a regular, and those regulars were generally in their 50s or older. In the brief time I was there, there was nearly no tip walk.

I hit the men's room at one point, and on my way back, my seat had been taken by a dancer. As I'm standing near where my seat had been, thinking about where I want to go next, I'm approached by a somewhat-attractive (5.5/10) Eastern European girl with blonde hair and an accent. She offers me a dance, and I ask if she's good. She says, "I have condoms and lotion in my bag, if that tells you anything." I figured I'd give it a try at $20/song. Red flag I didn't pick up on: she says, "do you need to hit an ATM?" I'm thinking no, I have a couple hundred in my wallet. How much can a couple of $20 dances cost me?