Card's views, whilst I find them deeply unpleasant, haven't put me off reading his work. But, learning about Marion Zimmer Bradley's background has had a somewhat different effect on me - more on this later.
The background is here:
Excerpts from MZB's Depositions
And it seems fairly clear from this that MZB's husband had a series of sexual encounters with young, teenage boys, that she knew of and chose to do nothing about. Indeed, she applied to adopt a young boy without informing the authorities of her husband's earlier behaviour.
This upset me more than Card on two levels - firstly it's about the sexual abuse of children which, perhaps because I am a parent, hits me on a deeper level than distasteful views on homosexuality. (Again, note, I am not condoning Card's views, I'm simply saying that, to me, failing to safeguard children - even her own - from a known sexual predator seems to be worse on my moral compass.)
But it also upsets me as a reader. As well as her SFF stuff, MZB wrote a book named The Catch Trap, which is the story of a life-long love affair between two men. It's a book I like very much and have read many times (partly because of the circus element of the story but also because the central relationship and characters are strong and real). But, crucially, at the time the love affair begins, one of the two lovers is about 14, the same age MZB's husband seemed to target.
Now, with Card, his personal intolerance does not seem to have hugely affected his writing - The Songbird, for instance, tells of a co-dependent (but non sexual) relationship between two men very sensitively, and Speaker for the Dead tells of a religion which speaks the truth of the dead and seeks to understand the person (and is presented as a model for tolerance - especially when Ender speaks for his hated older brother.) there are some books he's written which are closer to Mormon views, but generally he has been open about this being the case. (I could be being very naive, I grant, though.)
But, with MZB I sort of feel one of my favourite books, one that I would say shaped my wrirting, with its focus on characters and its closeness, seems to have been shaped by her knowledge of her husband. In this case, I'm finding it hard to divorce the author from the writing.