Voting is not based on IQ or any other qualification except that you have some kind of Valid Voting ID. We would not be a democracy really if you started putting various qualifications on who gets to vote.

I do not know anyone that would ADMIT to being swayed by Clint Eastwood or anyone else's endorsement. People do vote though on who has backed whom.

Oprah W. made President Barack Obama into the star he is by her endorsement in 2008. He was just a law professor/community organizer and writer of a few books. There were hundreds of these in the many law schools across the US.