Liberals think Sarah Palin is dumb because she didn't attend the right schools and doesn't accept liberal orthodoxy on numerous issues, especially abortion. Liberals are snobs; they look down on working class whites and conservative/religious jews. Working class whites don't have money or access to affirmative action, so they cannot even dream of attending ivy league schools.
Obama got into Columbia University as a transfer student from a community college, which is unheard of. He was an affirmative action baby all the way. And despite receiving mediocre grades at Columbia, he was accepted at Harvard Law School on -- what else -- the affirmative action plan. No such largess was bestowed on Sarah Palin, whose family led a hard-scrapple life without money. Sarah Palin earned everything she got through her natural gifts and hard work. She was given no advantages in life.