There is a wonderful little homage on writing in the margins by Laura Miller (@magiciansbook) in Salon. This article is full of anecdotes and incidents which highlight that “the ghost of that earlier reader” does not “deface” the book (even, or perhaps especially, the library book).
Kurt Tucholsky seems to be quite a favorite of librarians. His statement from 1931 on not to write in library books became a rather famous quote in our circles. (Though, it isn’t so much a quote by Tucholsky rather than by Peter Panter – but authorship and pseudonymity shall not be an issue right now. )