Yes, if it's non-fiction. If it's fiction, no. For fiction, the bio doesn't really make much difference. Case in point -- take Orson Scott Card. Here's a guy who (if his public statements are to be believed) is against same-sex marriage and believes that evidence disproving anthropogenic global warming has been suppressed. (Check out this link:
http://www.ornery.org/essays/warwatch/2007-03-04-1.html ). On both these issues, quite frankly, I couldn't disagree with him more. But you know what?
Ender's Game is still a neat book -
despite my personal disagreement with the author's views. There are many novelists in history who were disagreeable people but their books are great all the same.