ah, but under what of the man's pretenses (assuming any) did she WANT to have sex? likewise, under what pretenses did the man gladly fork over the dough? let's face it, men don't put out money & women don't put out sex unless they're expecting more. we all know that, so let's be honest about it.
Maybe that's how YOU feel, but I promise you this statement does not hold true for everybody. If i give somebody money, the only thing I "expect" is that they actually use it for what I gave it for them for. If I want anything back for it, I'll say so up front, and will only make such deals with people I know and trust.
Some of us aren't stupid enough to give cash to people we just met 5 hours ago, then cry about it when we find out they lied to us about what it was for. Likewise, you don't screw somebody you met a few hours before, then try to make him look like a horrible person for only wanting the sex.
And as far as "what pretenses was the sex under" it doesn't matter. Knowing that there are people JUST looking for sex out there, if you get down and dirty before finding out what kind of person they are, it's just as much your fault as it is his.