I've said before that I think that the American voter is stupid - and often times Trump supporters are just dumb. It's the Dunning-Kruger effect - often times they're too dumb to know they're dumb.
http://www.rawstory.com/2016/08/a-neuroscientist-explains-what-may-be-wrong-with-trump-supporters-brains/
All you have to do is watch a couple of interviews with a few Trump surrogates to see this in action. Racists would naturally flock to this like moths to a light.

And did you even bother to watch the vice presidential debates last night? Tim Kaine couldn't stop interrupting long enough to let Mike Pence get a word in edgewise. Also. Kaine sounded like a trained parrot trying to bait Pence with the usual Clinton talking points (which, BTW, he failed to do). So, I would say that there is something wrong with the brains of people who support Clinton/Kaine.