Mostly that they were local, had only vague connections, and that they left immediately afterward (I am not a one-night-stand-hugger ). I stayed pretty alert though, to make sure he didn't do anything unexpected.
I've had a few one night stands. I always let the guys and ladies know the ground rules before getting alone. Rules such as condoms will be used (even for oral), they will leave by sunrise and that this was merely a one night thing. I also had a few male roommates during those days so that eased my mind a little knowing they were in the apartment should anything go wrong.