I don't care what the book looks like, and there are some old book smells that are fine, but there's one specific variety of book smell that I've found in both new and used books, and I don't know what causes it, that makes me physically ill. I do smell books before I buy them, just to make sure they don't have that smell. Other than that, as long as the entire story is there without missing pages, I'm fine with well-loved books.