In my opinion, one night stands are ok if both people agree, with the same state of mind. Not for me though,
Again, I think a friend with "benefits" is ok if both people are ok with it, although this always turns out complicated as far as I am aware.
One night stands and friends with benefits arrangements have been openly admitted to by men for years, so have always needed a woman to do these things with.
Affairs, I dont know who cheats more. Whether it is men or women, I have no idea. Although they are a symptom of a marriage gone wrong and if a person stays with the person he/she cheated with, that hardly makes him/her a slapper.
I know plenty of women/girls who still hold out. Not one of my friends would let me go home with a guy on a night out and that works the same way too. I have seen my friends drunkenly agreeing to it and I have waded in and said if you are that keen you can call her tomorrow but tonight she is going home alone. Its a rule between us and I think you are very misguided about women as a whole.