The collapse of the barrier between popular culture and decadence has released a toxic mudslide of vulgarity into the nation’s family rooms—and just about everywhere else. There is almost no remote corner of this culture that is not marked by the toleration of vulgarity, or the outright celebration of depravity. Lee Siegel has seen this reality, and he doesn’t like it. “When did the culture become so coarse?,” he asks, adding: “It’s a question that quickly gets you branded as either an unsophisticated rube or some angry culture warrior.” Siegel wants us all to know that he is neither unsophisticated...