A person who regularly spends several hours inside a bookstore without the intention of ever buying anything.
The most despicable behaviors of a
bookstore bum include but are not limited to: pulling
umpteen magazines
off the rack and getting oily disgusting fingers on most pages then leaving every molested book and magazine adrift, reading in the prone position in the middle of an aisle, and wasting away sleeping in a chair that was provided for actual customers.
Actual bookstore customer: "I would love to take a look down the
non-fiction section but there is a grown man
sprawled out in the aisle like a child while
reading Harry Potter. They've got to do something about these bookstore bums!"