If he asks a girl out, how can she tell that he's asking because he is hoping to just hook up with her or because he is actually into her and wants to get to know her?
Most Helpful Guy
You can't tell for sure. You have to judge based on his behavior. If you're in a liberal north American city, the fact he's asking you on an actual date means something because people who just hookup tend to suggest going to someone's place -immediately-.
Expect some sexual interest, the question is do they show interest in other things as well? Do they want to do things other then go back to someone's place some of the time? Are they saying they want a partner, or just to 'have fun' and 'keep things relaxed and casual' which are code for casual sex.
There are some people who fool everyone... but that's pretty rare. Odds are if you watched your friend with a guy, you could tell if he was a normal horny guy wanting a girlfriend, or someone just looking to get laid. Look honestly yourself, and it's usually pretty clear.1
Most Helpful Girl
You can usually tell once you actually go out with him. I can tell pretty quickly. If he seems interested in you as a person and is asking you questions and paying attention to what you say, that's a good sign. If he jsut invites you over to his place right away... not so much.0