How is Holden himself guilty of being a phony in The Catcher in the Rye?
In The Catcher in the Rye, Holden denounces materialists--the rich, snobby prep-school types like Stadlater, Ernie Morrow, and the headmaster. He also says he hates movies, the Hollywood industry, and his brother for sacrificing his short story writing career to be a "sell out" screen writer. And finally, Holden condemns the oversexed Stradlater because he brags about his escapades. Instead of these "phonies," Holden champions the innocent and uncorrupted: children (Phoebe), nuns, and James Castle (who committed suicide rather than conform).
When it comes to money, movies, and sex, Holden is indeed a kind of phony. When it comes to money, Holden is a bit of a hypocrite. Sure, he gives money to the nuns, but he also blows through it to go on his runaway adventure, staying in hotels, paying for cab fare, buying drinks in nightclubs. He also goes to the movies more than a few times, even with Ackley. And he proclaims himself "sexy" throughout much of the novel, and he tries to pick up girls, even a classmate's mother (Mrs. Morrow), every chance he gets. But, don't forget, Holden is at least admitting his phoniness to us through his actions in the novel. So, he is a self-aware phony even though he does not explicitly denounce his own actions.