Over the past decade I've seen too many library books that haven't been taken care of by borrowers. The problem is not torn pages or writing on the books, though I see that, too. The biggest problem I see (and frequently) is what you might call "foreign matter" on book pages.
Sometimes it looks like food--grease and stains and blobs of unidentifiable substances. (At least, I hope it's food; the alternative is even more disgusting.) Occasionally there will be a dead insect, or maybe a lone wing or portion of a carapace--all that's left of a bug that landed on a page and was crunched by a reader.
And then there are the unpleasant odors drifting from opened books ... I have had to put a few out in the open air before I could read them.
Can you people take better care of the books you borrow? The occasional coffee or soda stain I can understand. But what I'm finding on pages nowadays is the result of sheer carelessness. Try not treating library books like they're your own. Treat them like they belong to someone else--someone you respect.