”Who are these people?” goes the generic Seinfeld punchline. In this unauthorized biography, they’re his ax-grinding ex-girlfriends and abandoned college buddies, upon whom Oppenheimer relies so heavily that the book reveals more about their own bitterness than the comedian. The dirt-crazed profiler (who previously eviscerated Martha Stewart) uncovers no substantial gossip about his subject’s decade-defining sitcom, and little new about how he filched his bride, Jessica Sklar, from her first husband; so to compensate, he overdemonizes the only minutiae he can find, like the fact that Seinfeld never donated money to his late father’s temple — the bastard! And throughout, the author is obsessed with discovering if Seinfeld is gay, even when his sources repeatedly deny it. Not that there’s anything wrong with that? No, everything’s wrong with this piece of hackwork.