The problem with this, first of all, is that a lot of what was drafted into the "camp" camp was not really distinguished by failed seriousness; it just looked that way thirty years later. Sontag writes: "Genuine Camp -- for instance, the numbers devised for the Warner Brothers musicals of the early thirties (42nd Street; The Golddiggers of 1933; ... of 1935; ... of 1937; etc.) by Busby Berkeley -- does not mean to be funny." Well, that's a matter of opinion; I'd say that Berkeley's outlandish gimmicks and nutty commentaries on the subjects of the songs he staged (putting everyone in money costumes for "We're In the Money," etc.) show a lot of deliberate humor and awareness of their own silliness. And Beerbohm's Zuleika Dobson, which she includes at the head of her "canon of camp," is one of the most self-conscious, deliberately silly and stylized novels ever written; there's not a bit of that "private zany experience" that Sontag treasures, because the zaniness is all consciously built into the work.
Claiming to see unconscious humor or weirdness in works that are deliberately funny or weird is part of the tendency to assume that past times were less sophisticated than our own. If you assume that people of a previous generation couldn't have understood irony or self-conscious humor. Thus it's easy to recognize a then-recent work -- like Beat the Devil -- as deliberately campy, but it's harder to recognize that maybe the people who made the so-called camp classics also knew exactly what they were doing, and that audiences of a previous generation were sophisticated enough to pick this stuff up. The "camp" aesthetic implies that many works have a hidden meaning or hidden value that only the sophisticated can see, because in fact it's a meaning that's unintentional; the sophisticated make that meaning up for themselves. This can be worthwhile, but I think it's more worthwhile to try and let go of patronizing assumptions about old pop culture and mass culture in general, and just try to enjoy things for what they are... whatever that may be.
The definitive put-down of "camp" was in a Mad magazine parody of the '60s Batman series, which ends with "Bats-man" telling "Sparrow" why their show is so successful:
BATS-MAN: For years, networks tried to reach hip viewers with intelligent programming like The Defenders and Playhouse 90. But then they stumbled onto an important discovery: give the hip crowd garbage and they'll call it "camp" and eat it up!
SPARROW: Holy Nielsen! You mean the swingers are really squarer than the squares!