No less a documentary giant than Michael Moore has famously touted "Winnebago Man" as the most hilarious nonfiction film of all time. I wouldn't call it that exactly, but this burrowing study of an irrepressibly profane RV pitchman-turned-YouTube sensation is indeed remarkable, in part because you don't need to find "Winnebago" funny in order for it to rev your engine.

Much of the documentary's recorded dialogue simply can't be printed here. Jack Rebney, the Winnebago salesman whose no-budget commercials went viral before the Internet, flaunts a colorful vocabulary to rival that of Al Pacino's Scarface.

Contracted to sell RVs on-camera in the late 1980s, the volatile Rebney vulgarly mocked them and the whole concept of marketing. Via milky VHS dupes of his F-bomb-laden bloopers, these shenanigans made him vastly more famous than any polished TV ad would've done.

That Rebney created a kind of curtain-peeling performance art out of his huckster drudgery ("I don't give a *#+@!") has mesmerized many, including filmmaker Ben Steinbauer. The young documentarian begins "Winnebago Man" by going in search of a legend (or "legend") who dropped off the map even as his Internet hits went through the roof.

Steinbauer hires a private dick to find the "world's angriest RV salesman," who hasn't been heard of since around the time that Moore's "Roger & Me" hit it big. The film's first genuine surprise isn't that Steinbauer manages to locate the reclusive comedian (who's surviving his 70s in remote Northern California), but that the ornery Rebney proves a willing participant in the film, even cleaning up his act and sounding vaguely ... professional?

Like "Salesman," "American Movie" and countless other comedic documentary portraits of artists-in-their-own-minds, "Winnebago Man" openly invites the question of whether its subject deserves the camera's rapt attention.

Certainly this hammy Don Rickles of YouTube believes he belongs in the center of the screen, even as he pretends to loathe Steinbauer's opportunistic methods and unleashes once again -- if only for nostalgia's sake -- the foul temper and filthy verbiage for which he's known. (New targets of Rebney's old-style wrath include former Vice President Dick Cheney and the general depravity of contemporary culture.)

As aging Rebney turns increasingly philosophical in his rants, while twentysomething Steinbauer clears space in his film for historical consideration of "reality culture," Roman spectacle, "cyber-bullying" and media theory, the movie becomes oddly deep and even poignant. The Winnebago man's frighteningly sizable legend seems totally beyond him until he meets his public in the flesh -- and urges them to say what they feel.

Worse advice has been given, particularly by profane YouTube sensations.

Rob Nelson writes regularly about movies.