Funnily enough, I seem to be a magnet for friends that have some psychological issue or the other. I guess it is true what they say, birds of a feather flock together. I myself feel uncomfortable in the company of people who are "normal" i.e., extroverted and socially competent. I tend to find the latter type of people to be the most judgemental.
However, hanging around with people with psychological issues can have its flip side too. Depending on their affliction, they can be unstable and volatile or narcissistic. I had one friend who suffered from depression, but had a horrible habit of always putting people down to feel better about herself. She particularly use to pick on me and embarrass me in front of the group. Another one of my friends was OCD and suffered from low confidence, he use to hang around with me and my group of friends all the time, then all of a sudden when he found a new more "normal" group of friends he dropped us in an instant, changed his number and never met up with us again. I thought to myself, fair play to him to move on in his life, but how selfish of him to just drop us like that as if we never mattered. Another one of my friends, who is still one of my best friends, is one of the worst listeners you would ever meet, he has the attention span of a goldfish and he never sticks to a single topic when you are talking. He also has a horrible habit of constantly interrupting you and second guessing what you are going to say, though he is invariably wrong!