Actually, although I remember attending and hosting sleep-overs as a child, I couldn't tell you a single thing, good or bad, that happened at any of them. I can describe various other parties from the same time period. That may explain my stance that sleep-overs are not a necessary rite of childhood. I'm not truly against them, either, since I have permitted my son to spend the night at a friend's house whose daughter is one of his best friends.
I trust them, and when it comes right down to it, that's all I really have to say about it. He's not allowed to spend the night at my mother's house without me because I have BIG problems with some of the things my mother does lately, but my ILs, my dad's ex-wife that I still refer to as my stepmom, and my brothers are all fine by me. My dad and his new wife I'm not so sure of, but recent developments have me leaning towards "okay." That's a crazy, and OT, story all by itself.
That said, unless I have issues with a particular child's behavior, sleep-overs at our house are okay. I have no problem adhering to rules other parents have that are stricter than mine, whether they be about food or media content or whatever, but I need to be confident I can expect the same consideration in return.