Some of these "crazies" don't have mental issues, they are greedy, self-centered, and and have learned from years of experience how to use their skills to live off other people. "Learned helplessness". Nice work if you can get it (and want it)!
IMO, no one who has responded on this thread has come across as mean-spirited. It's natural to notice the behavior of others and just as natural to comment on things that catch our attention. Odd behavior runs full spectrum through the human race: we chuckle at the odd things babies do or say, at the antics of children and the childlike. Sometimes the amusement is tinged with bitterness but that's a far cry from disparaging people with mental issues. It's not unkind to be human or to notice other humans, in fact, it's.....human!