I don't mind weeding if it's to make space because you've got limited space. I mind it if you've got empty shelves already and you think that people borrow more books when you've got lots of empty space on the shelves that do have books...

I looooove booksales though. Keep those books a circulating! And I don't mind a used book that has little annotations in it, either. Did any of you ever read "84 Charing Cross Road" by Helene Hanff? She expressed that feeling of camaradarie with the reader before her better than I've ever seen it done since.