He says "dirty" because he's talking to a young woman. He thinks of her as innocent, and I'm pretty sure baiting girls with naughty comments is one of the things he'd just do. Maybe I should go back to "naughtier", though...

You're right about the chemistry thing, though. I didn't really establish anything. It ends before it begins, and it's not from her point of view, so that's tough. I'll think on it...maybe at the part where he talks about liking to have her come I can fit something in.