I can't read anything by Marion Zimmer Bradley anymore. Whether it's a book I've already read, or a new one... it's just not possible. I do think she's a good author.

I also can't read Tolkien anymore. I read the books 4 times in a row when I as 13-14. I can't read it anymore. I have to admit, I read it in Dutch (one of the few English books I've read in Dutch), and it's better in that language than in English.
I do think that Tolkien is a good writer.

I can't read anything by John Grisham. It's just too tedious. I don't think he's particularly good.

I can't read anything by Dan Brown. I don't think he's good.