Dear Library Patrons,
When I ask you politely not to reshelve your own books, please don't tell me that it's okay because you know what you're doing. I don't care if you're a library volunteer, a librarian from another system, or Melvin freaking Dewey. Don't reshelve your own books!
Say you're right and you do know where your book goes. That's great. But now we've let you do it and there are ten other people who think that Tom Clancy goes in 398 in nonfiction and that, friend and neighbors, is how we lose books.
I'm not trying to insult you. I'm sure you're a very intelligent person. But since you are an intelligent person, you can probably figure out why I don't want you to reshelve your own books and stop doing it.
Just put them on the shelving cart, for god's sake.