Buy the 2 booksfrom an indie, via Bookshop.org. Not the other guy.
What it tells you
The pilot gives Mooney's two book moments. Beck buys Desperate Characters, and a customer trades up from his Dan Brown to Franny and Zooey while Joe and Beck watch. Joe does his profiling at the register.
Beck's copy turns up again away from Mooney's, on a pile of paperbacks with a phone parked on top of it. Joe is the one who rang it up, which on this show counts as a background check.
Paula Fox's 1970 novel follows a childless Brooklyn couple through a long weekend after a stray cat bites the wife. It went out of print more than once, and Jonathan Franzen's essay in Harper's is credited with bringing it back for a 1999 Norton reissue. Joe rings it up and starts a relationship that goes about as well as the Bentwoods' marriage.
Salinger collected two New Yorker stories about the Glass family into this 1961 book. The customer picks it because it looks respectable next to a Dan Brown, which is the book equivalent of wearing a blazer to a gas station.