There was one house that kept theirs well stocked with interesting things, but someone or someones with cars would come and steal everything out of it. The family gave up eventually in great sadness and gave the library to a neighbor. I haven’t seen any big sudden emptying-outs in quite a while, so maybe it was just one asshole who moved or went to jail for something or who knows what.
One library was taken up as a home by wasps (and yet I could see through the window that the books kept changing, so they must have been somewhat docile wasps!), and one library got warped in rain and their books get moldy in the rainy season, so do keep paying attention to the condition of your library.