Since I started writing, a strange guilt plagues me whenever I read: I feel like I should be writing instead. A really good book overcomes this guilt, because then I consider it research, honing my craft by reading expert writers.
My own study of what I want to write and how I will do it makes me intolerant of what I consider mediocre work, so that I often don't finish a book if it hasn't grabbed me by fifty pages or so.
I've been trying to expand my knowledge of writers' names, since I often meet people at cons and it's embarrassing to admit a) I've never heard of them or b) I haven't read their work. This creates some interesting situations: I may have stopped reading the book of a person I'm introduced to because it failed to appeal to me as a reader.
Luckily, thirty years of reading student work trained me to look for the positive. There's very little published work that doesn't have some redeeming quality. After all, it appealed to someone in the industry. So while I may not like a writer's work, I understand that I'm not the end-all expert on writing. That's probably something all of us need to accept.