The internet is a venue for those with low self esteem and various other personal issues to lash out at others and vent because of their own inadequacies. Obviously not saying every single person online is like this, but you see these types on every website you go to. The most common term for these people is "troll", although they don't have to be classified as such to have those issues.
I have seen some complete nutjobs on many sites(not just GNR sites), and its a tad worrisome that such people exist. They should be at a psychiatrist's office instead of surfing the internet.
I remember a few years back, this chick from mygnr joined my old site. I knew her a bit at mygnr, and something just wasn't kosher about that situation. She walked into our chat room acting like she owned the place, and at that point I had to lay the smack down and see if my instinct was correct. I started lobbing questions at her and getting her comfortable, and then dropped a few sledgehammers on the room when asking her what her shoe and pantie size is. She got totally flabbergasted, couldn't answer what should have been a simple question for a woman, bailed out of the room and never logged in to the site again. Men impersonating women on the internet have trouble with such questions because men who do that have little if any experience with women.
A few weeks ago I saw her posting in an off topic section there. I laughed because nobody realized they were actually talking to a dude.