I think it is because Bush Derangement Syndrome has gone to dizzying heights. The average vacuum brained TV watching American is currently clueless about reality. Eight years of media pounding on the President has left the shallow minded with the belief that everything is " Bush's fault."
These people have no idea how bad their lives will truly become if Obama and his marxist ilk are elected.
You've probably hit it as it's been relentless, and given the lack of exposure to things political what they see is most likely negative.
Obama could look and sing like Elvis Presely but I wouldn't vote for him. Too shallow, a whole lot of clean, articulate, nothing.
Bush should have gone to D.C. to be a 'divider'. His mistake was reaching across the aisle ('compassionately') and getting his hand stomped. Now, McCain is poised to do the same thing. Heck, the Left could lose the election and still come out ahead.