I have noticed that it is easier to enjoy actors who do not make their politics well known. Or at least actors the media don't make it a point to let us know what their politics are. Even though I can assume what they believe, it is easier to believe they are a character they play if they aren't showing how they really are all the time.
The thing is lots of people like to look up artists' political donations regardless of their being vocal about it. If you do that you may as well not see anything.
Artists like the Dixie Chicks, for example, who mindlessly spout off against America while singing about mostly drivel don't get any respect from me. It's like they are saying, "Oh, by the way, we hate Bush, too. And now here's something from our new CD."