Gregory Hays in the New York Review of Books:
Why is this piece funny? The answer, according to one popular theory, is that humor is grounded in incongruity. Certainly a good part of the fun here lies in encountering familiar figures in an unfamiliar light: H.L. Mencken as ill-fated condo salesman, or Ring Lardner as “human flotsam” churned up by the “Colombia drug-smuggling underground.” And of course the whole piece rests on a basic crossing of verbal wires (what if Dwight Macdonald were John D. MacDonald?).
A rival explanation holds that laughter springs from a feeling of superiority—a “suddaine Conception of some Eminency in our selves,” as Hobbes put it, “by Comparison with the Infirmityes of others.” Geng’s squib might seem to offer less support for this theory. But look again. Obviously the piece requires some generic familiarity with hard-boiled detective novels and their blurbs. But it also helps to know something about the individual authors. For the descriptions are not as arbitrary as they may appear. “Petite, blonde” Jane Austen’s unlicensed “health spa” is Bath transported to the Gulf Coast. The real Cyril Connolly’s bait box really did harbor a poisonous cargo. Benchley was adrift in his later years, his talent drained by Hollywood (“the Fun Coast”) and the bottle (the “derelict marina”).
More here.