How do you decide about normality?

It depends on what they're looking for.

If they want to know if it's common then I'll tell them if it's something I do or not. If they want "normal" then I'll tell them if what I believe they're doing is destructive or not.

Well I have standards

Sometimes I base it on what I percieve as normal. But I also know that normal for me is very weird to some people. I try to take that into consideration when making a comment. And sometimes I like to point out the difference.

Based on what I've experienced, seen, talked about, read, learned, ect, ect. When I rate something 0% normal it's only my opinion. But again, there's a lot of people here who would find things I find normal abnormal and vice-versa.

Well since there isn't really a universal definition of "normal", my answers are obviously effected by my perception of what's normal. It also depends on the post. It's a mix between a lot of things. I avoid letting my taste/preferences effect it, and I do try to be objective (not sure how good I am at doing that, though:P).

To be honest, though, I don't spend too much time thinking about it. A lot of the time I don't even tell the OP whether their behaviour is abnormal or not. And whenever I leave my opinion in a comment, I try to make sure that it can't be read as anything other than my opinion, because I'd hate for anyone to think it was a fact. It clearly isn't.

Well, comparing one's penis to another seems... OH! You meant..

Normalcy, at least in this category, is based on the collective, for sure. As far as thought processes go, it's still up to debate on nature vs. nurture, so the majority is what we're stuck with.

Varies entirely based on more factors than I could describe here. If you want to pick any answer of mine (apart from this one), I'll probably be able to tell you what was going through my mind and why I judged something normal or not normal.