Kevin Drum linked to this, and it’s still great, so I’ll link to it, too: Kung Fu Monkey: Lunch Discussions #145: The Crazification Factor
Too funny to excerpt, just go read it.
OK, one part explains why Bush can’t go lower than 27% in the polls,
Obama vs. Alan Keyes. Keyes was from out of state, so you can eliminate any established political base; both candidates were black, so you can factor out racism; and Keyes was plainly, obviously, completely crazy. Batshit crazy. Head-trauma crazy. But 27% of the population of Illinois voted for him. They put party identification, personal prejudice, whatever ahead of rational judgement. Hell, even like 5% of Democrats voted for him. That’s crazy behaviour. I think you have to assume a 27% Crazification Factor in any population.