For me it depends on if it's fiction or non-fiction. For fiction, if it's a good read, I don't care what the author is involved in.
For non-fiction, the author's personal opinions and views often play a big part in how the material is written. I wouldn't read a book on paganism written by Pat Roberts, or a book on animal rights written by Ted Nugent.
I'd definitely read a book on animal rights by Sweaty Teddy. i can see the title now: Animals Have The Right to be Tasty.