I just had 2 girls come into the library from a biology class; they wanted to swab books for a bacteria experiment they're doing in the lab.
"What do you think is the most checked-out book in the library?"
"One of the Twilight books. Definitely."
They agreed with me and set off for the fiction collection, Q-Tips and petri dishes in hand.
"We're going to see which is dirtier: the girls' bathroom floor, or the most checked-out library book. We think the book."
That might be stretching it a bit. But I wouldn't be surprised to find that that series while not "dirrrrrrty", is indeed dirty.