Locobot: My uncle is no longer allowed to carry a gun if that's any indication what those people around him think
It also helps that another of my uncles - on the other side of the family - is an attorney in the same court system and on track to being a judge, so I hear stories from that angle. Finally, my former sister-in-law is a licensed social worker who deals with a lot of mentally ill people and we've had discussions that my uncle seems to have a mild form of schizophrenia.
And no, the Santa guy is not in the same league as the guy who threatened our campaign manager. He's certainly harmless. Doesn't mean he's entirely mentally competent though. In fact, I had my own theory of him which is that he seems to be in the early stages of Alzheimer's (he's 80). In conversation, he reminded me a bit of my grandpa (who has Alzheimer's). Anyway, recognizing that someone is a little kooky isn't a slight on their character, it's just a matter of acknowledging some of the more interesting personalities that you come across in this and similar lines of work. And it's common enough that if you have a good relationship with the other campaigns, it's fairly normal to call them and give them a heads up if you think that person may go into their offices as well.
Sabrina: That exactly what I'm getting at. Most people are well intentioned, they just have very unique attitudes and approaches is one way to put it.
Sticky: I think you're very right about available time being a factor. The general theme I've noticed is that the people who are not quite 100% "there" are either a little older, or if they're younger then they do have trouble holding down a job (this is information that they generally come forward with through conversations).