I absolutely judge books by their covers.
Debates also rage in my head about the usefulness of a book depending on its size. If it is big and bulky, I ponder at its usefulness to my research in relation to its awkwardness of carrying it to my carrel.
I leave my books on a table when I am done. I used to work at a public library and know what those carts at the end of the aisles are for. I just think that the library is too orderly and want to mix it up a bit. Plus, I am always intrigued whenever I see a stack of books. What was the patron before me studying about?
I have consumed snacks AND beverages in the library. SHHH. But I've never written in/torn a page from/dogearred/damaged books in any way. Not yet, anyway. I have also fallen asleep with my head on my desk at the library before. More than once, in fact.
I am not sure if it is the librarian in me or the ranger in me (or the fact I don't care what people think about me) but I have asked people to "shush." Nicely, always nicely.
The library is one of my favorite places, ever. I love the smell of books and the ideas bound between their covers. I love the atmosphere of the library (it is quiet and I can hear myself think and I don't get distracted with home-chores). Even though I am not a fan of germs, I love the feel (to include the paper dust!) of a book.