I'm in charge of the browsing paperbacks collection here at Claremont. The collection consists mainly of books that come to us as donations. Whenever someone drops off a bag of books I hop over and paw through it. Usually there's a book or two worth adding to my to-be-processed stack in the workroom.
It's simple processing. A barcode and radio frequency ID tag (RFID), a label to indicate genre (nonfic, fic, sf/fantasy, romance, mystery), a little plastic to reinforce the cover. Unlike the majority of the items owned by the library the browsing collection doesn't have to go through our cataloging librarians; you can't look them up in the catalog; what you see is what you get.
General fiction is popular. Nonfiction does fine. Mysteries? Yes, more or less.
But romance and sf/fantasy? Not so much. There are some name romance authors who go out but many paperbacks on the spinny racks go round and round and round, year after year. I've long had fewer sf/fantasy but the rate at which they go out is about the same. The other problem is that people just don't donate romances and sf/fantasy, so it's hard to keep the collection from getting tired. Maybe readers tend to resell the genre stuff at Berkeley's used bookstores. Dunno.
Anyway, I finally got a bagful of goodlooking romances so decided to refresh the collection. I reviewed everything that'd been swinging about the carousel and found many that hadn't been checked out in 2 or 3 years. I threw those away. I've reduced the romance collection by about a third. As I also obtained some more sf I'm going to equalize the romance and sf collections. See if they really do have about the same size audience.
I'll let you know.