This topic is exactly why I don't really go 'out of my way' to learn about most heroes. However, I tend to look past what they did (provided it wasn't/isn't too horrid). For instance, I read Stephen King for years and knew he was an alcoholic. That really didn't change my perception of his writing. And I could care less about Anne Rice's spiritual beliefs.
That said, if someone I admired and or enjoyed their work (art, literature, movies, etc...) were to have done something like it appears Marion Zimmer Bradley did, I couldn't look past that. There's a clear line between someone who might believe differently than me, but is not hurting anyone (I'm speaking in the case of different views on a variety of topics from politics to religion and anything in between), someone who has an addiction or acts out in public (Charlie Sheen anyone) and someone accused of hurting children or causing intentional harm to anybody for that matter. If it was proven that they had in fact perpetrated the crime, I wouldn't be able to enjoy their work any longer.