Evidence inconclusive. On one hand, a guy who just wants sex will certainly try and seal the deal on the first date. Although guys who just want sex don't usually go the traditional date route when there are so many bar skanks to be had.
On the other hand, a guy who's legitimately interested in a relationship with you also wants to have sex with you on the first date. Make no mistake, if he could order that from the Chili's Menu, he'd buy three.
However, a guy who wants a relationship will usually pretend he DOESN'T want to have sex on the first date, so that you can't be creeped out by how incredibly horny he is until it's too late to back out gracefully. See, us relationship-wanting guys are always two steps ahead.
Unless the date goes really well, and they feel like trying for sex on the first date isn't going to jeopardize anything, or if you're both twice-divorced and in your fifties and just sick of all this dating bullshit.
Hopefully some of those immutable dating laws (ie, my casual observations) will help you determine whether or not to have sex with the guy I imagine has been waiting quite a while while you stall in the ladies' room, iPhone in hand, waiting for a response to this question.
Are you assuming that he wants to have sex with you on the first date, or do you know this to be fact? Like any guy, he wants the sex, but the fact that he's taking you out and trying shows that he probably isn't looking for just a hookup. Like the Funny Guy said, there is a readily available supply of "bar skanks" to fill that role.
If you're having doubts, test this guy's resolve and hold out. If he isn't upset about it and still wants to see you again, you have a shot at a relationship, but remember that those take time.
I know for a fact... well, maybe that's really a conceited thing to say, but I'm fairly certain 99% of the time. I've been single for about a year and a half now, coming out of a very long relationship (7 years -- I am now 28). I've been dating various people for the last four months or so, on average, two to three weekends a month. I guess I should know how to deal with this by now, but I really don't.
I met a guy who I find mildly interesting, and he wants to "go out with me sometime". I have to call him back at some point! But the last few months of dating has been really bizarre for me...
Almost always, the guy invites me over after the date and at some point, I guess there's gotta be some sort of making out involved. I love kissing (only if I really like the guy) but it just seems like it never ends there and before you know it, there is some weird groping session involved. I don't always sleep with them -- in fact, it's really rare that I do. It's just that I've been told by so many people that men would only want to sleep with you on the first date because they want ass and not a real relationship. It left me wondering if I'm only sex-able and not really date-able! Just had to be sure...
So that's why I was asking :) Because the way I see it, if I sleep with someone on the first date, it doesn't necessarily mean that I only want sex and will never call him back. Just needed to hear it from someone I don't know who will give me an honest opinion.