I've had several. 85% percent of them were with a condom, most said they were on the pill.
It's usually really good sex. lol my last sex session was a one night stand. that was like 9 or 10 months ago.

Honestly, I don't consider any of my one night stands dirty or "loose".
Quite the opposite, I respect them for being human enough not to deny their sexuality.
if that made any sense.

[edit] don't get me wrong, I would MUCH rather have sex with someone I care about. most of my one-night stands involve clubs and some drinks lol