I believe Obama said he heard his grandmother make racial remarks that bothered him, not that she was a racist. Unless, of course, you can post irrefutable evidence that he did indeed call her a racist? I believe in one speech he called her a "typical white person" while refering to how her generation was raised, but that's hardly calling her a racist or throwing her under the bus.

And of his mother, are you implying that he was greatly disrespectful of her?

If mere questionable associations, although not quantifiably adverse, are truly such a disqualifier in your presidential selection process, then Ron Paul should be very pleased to know he's got your vote. I don't see how you could vote any other way with good conscience.