I had an unintentional one-night-stand once. The guy made me think he was romantically interested in me to get what he wanted- me, in his bed. I gave in and we had sex, and he immediately informed me that he wasn't "in the right place" for a relationship, and just wanted to be friends with benefits.
I just didn't enjoy the experience. I can't get into sex without some sort of relationship, some form of commitment. Sure, some people love no-strings-attached sex, but I'm not one of them.