It's makes it feel less like a paid sex session.
It turns me on to give such pleasure to a beautiful women. I love pussy so why not spend a bunch of time exploring one.
It's boosts my ego when I can give her six orgasms with just my mouth. I know that no guy has done that for her before because young guys are fast and selfish.
It makes her very grateful in return. Sure she will probably do much of what I want cause I'm paying her too. But if I've just spent 30 minutes eating her pussy, she wants to please me. In other words she does it much more enthusiastically.
It makes me feel less like a selfish bastard.
Maybe most important, you can much more easily develop a great long term sexual relationship with a dancer if she gets sexual pleasure from it too. It makes sense that she would be more enthusiastic if in addition to money she also gets sexual pleasure.
Long story but I would not be with the DS in the way I am if I hadn't eaten her out the night we met. She really is a non extras girl in a non extras club, and I got sex from her only because I gave sex to her first. Sure she wanted money but she had no promise of any extra money the night we first had sex. She was responding to what I did for her in doing the same for me. This might not be true for a lot of dancers but this was my experience.