I would never make my girlfriend swallow, unless she was into that. When I was younger I thought it was great cause maybe I watched too much porn, but as I got older and developed respect for the girls I liked, I kind of felt it was a bit degrading for them so I wouldn't let them do that. Now, only if I don't care for the girl or if I thought she is the slutty type, then I wouldn't mind, but is not something I'm into. Interesting question.
Personally, I think it's really sexy. I've asked my girlfriend how she felt about it and she's stated that she doesn't want to do it because she would feel dirty and that she doesn't want to taste it. I've respected her feelings and not asked her again to do it. Comes down to that stuff they call "Compromise". :)
It is a big turn on for me it just completes the whole deal! It's not that I would get mad if they didn't swallow but it is kind of a turn off if they make you cum then get up to spit it out or just let it run all over you. It's really a turn on if you back off just a little and let them watch it squirt in your mouth too.
I find it very sexy as well. I get even more turned on when I cum and she is willing to swallow it or just simply take it in her mouth. With me it is that taboo thing that not many woman are willing to do, yet, she is willing to do it for me. I would never ask her to do it or get upset if she didn't, but when she does it out of her own free will, it's like she is willing to do anything to please me and that is a big turn on for me. So I guess yes, it is a turn on. Be careful as to not earn a reputation of the "swallowing queen" if things didn't work out between you two. You should take precautions as to who's sperm you are swallowing and why, unless you just like it to please yourself as well. Take care of yourself always.
Yea, most guys think it's really hot, and you don't have to be a slutty girl to do it either. You either get used to doing it or you never do. Or if you just hate to swallow guys like to see it go on the girl. But only if your comfortable doing it, I think if any guy makes you do something then he isn't the right guy.