*Disclaimer*
*This is all anecdotal evidence, and probably doesn't apply to all areas*
Perhaps it's only my local area. When I was in high school, the anime crowd was a subdivision of the mentally abnormal crowd. I'm sure it didn't start out that way, but once enough of the 'less than functional' people got in, it became a gateway for all the schizophrenics, fetishists, manic-depressed, and otherwise mentally/socially unstable kids. Perhaps they were just too open with their tolerance, but it quickly became overrun with the larpers, the furries, the wiccans, the jailhouse bisexuals, and the generally socially inept. I'm sure there could be some good in the genre, but all of this combined into one massive shit storm. Basically everyone would get together and watch the weirdest stuff, and not weird in a good way. These people didn't really surface until the high school age, but many of these people were treated like shit during what I've seen at elementary and middle school, so it's understandable why they would ban together and create this weird subculture.
For a silly example outside of school, a friend gave me a foot in the door for a job at a kennel. On my first day, I met a co-worker with disgustingly dyed purple-ish red hair. During the first conversation, I said I was new and if she knew ____. She said she didn't like him, because he doesn't like Final Fantasy. Later, she said her therapist suggested she work with animals, and the animals help keep her sane. She also sings and talks to them like they are people. She's a pretty good example of the kind of anime people that are around here.
About an hour and a half away from where I lived, I had a friend named Chibi, who was a devout anime girl, and talked about how her friends love to get together to binge on anime series and heroin. Actually, she was a pretty interesting person, after you get used to the illicit drugs and her bright blue hair.
One time I was slightly coerced into going to an anime convention in DC with a couple of friends (she said it was for video games, oh the lies). The people in their 20's seemed to be a lot more calm and composed, but the under 20 crowd displayed huge amounts of fucked-uppery.
I won't say they're unfriendly people, most of them get way too absorbed into anime, and become some strange deviant monstrosity. Obviously, my experiences with them are very, very biased.