Like organ grinders' monkeys, they've been trained to respond on cue with the media-abetted talking points:
"Palin's an idiot."
"She's so stupid she says she can see Russia from her house."
"Palin's a quitter"
"I hate Palin"
There are a large number of traditionalist Republicans who felt that Palin in 2008 was not seasoned enough.
I am one of those traditionalists. I did not like Palin for that reason. I did not like McEnroe either when he first started, but later I did. I did not like Agassi the teanager, but liked him better later. I generally do not like phenoms, but after a phenom grows up a little, then I like them. I did not like Kobe at first but really appreciate him now. Ditto for Shaq.
A lot of republicans tend to be traditionalists in this way.