When I was in University I had a lot of classes with a guy who had Tourette's Syndrome. The guy used to twitch and swear pretty much constantly. This could get pretty distracting in lectures, but most people were willing to put up with it because they knew it was involuntary.
What got interesting was taking mech classes with this him. Mech involved drawing extremely precise drawings using a number of sharp instruments such as pencils and protractors. At the end of these classes all the students would hand in their work. The work was partially judged on the appearance of the drawing: consistent line weight, straight lines, clean erasures, etc.. Because of this most people made sure to keep their work as clean as possible. Often when a serious mistake was found, it was better to start over with a fresh sheet of paper rather than try to erase the original work completely. The guy with Tourette's didn't have that option. His work was always perforated with thousands of pinpricks. There were so many holes in the paper that seeing the sketch was next to impossible. Many people wondered how the professors managed to grade his work.
Despite his affliction, this guy was extremely smart. He did very well in all his courses, including mech. But the other interesting thing was that he was not a very nice guy. He was arrogant, condescending, and even when his Tourette's wasn't acting up, extremely annoying. He would insult people, pester them with personal questions, and brag about how good he was. He was like this with everybody, even people who seemed to be his best friends. Despite this, he appeared to be well liked. Many people treated him as a friend - and the people who treated him best were often the people at the center of the "in" crowd. I always wondered why.
My best guess was that it was a combination of factors. One undeniable one was that people felt sorry for him. They knew he must have felt different from everybody else, and wanted to be nice to him. But I think another factor was more important, political correctness. To begin with, it was seen as bad to be unkind to someone with a disability, even if that person exhibited behaviour that was boorish, so being unkind to him was a no-no. But it seemed that there was more to it than that. I think that one of the most important parts of being in the "in" crowd was showing a certain attitude towards racism, sexism, sexual orientation, disability, poverty, religion and anything of that nature.
While I think it's wrong to judge someone solely based on one of these factors, I think it's far more important to think for one's self. It always bothered me that although my University did have frequent protests, they were without fail PC themed protests. It's hard to have an interesting and intellectual debate between "We need to build a few more homeless shelters" and "We need to build a lot more homeless shelters and put more money in welfare"