If you separate sex from love, use protection, are honest with your partner (and yourself) about your expectations and you are respectful, then there's no reason why you can't enjoy a casual fling.
It depends on the person, the sitch, and your frame of mind. If you're drunk and make bad decisions, you'll surely feel bad. If you're of sound mind and so's your partner, it can be great.
The fact that you're worried you'll feel bad about yourself later is a sure sign that casual sex is not for YOU, that you WILL feel bad about it. There's something to be said for going with your gut.
A one-night stand might feel good at the time, but eventually empty sex without any emotional connection or intimacy will inevitably make you feel sleazy. Why start now?
