A word of warning to documentary lovers: you might have to hire your own private investigator… A word of warning to documentary lovers: you might have to hire your own private investigator before you can enjoy your favorite genre again.

This summer’s “Exit Through the Gift Shop” — the story of a French shopkeeper who follows street artist Banksy around and eventually, with Banksy’s endorsement, becomes a famous street artist himself — is just the latest in a series of maybe-real, maybe-not documentaries sweeping the nation.

The film piqued journalists’ skepticism for several reasons: 1. the shopkeeper, Thierry Guetta, is so over-the-top it’s hard to imagine him as a real person, 2. Banksy, the director, is a prankster to put your roommates to shame and 3. the film’s story is, at best, unlikely.

But as mentioned, “Gift Shop” is only the most recent film to capitalize on its own ambiguity — perhaps catalyzed by “The Blair Witch Project” (1999) — so-called “documentaries” have boosted themselves in the public spotlight because of their squeamishness with fact.

To some, this evasiveness may seem inane: what, exactly, would be the problem with labeling these films “dramas?” Why the assertions of validity? The cynical answer — the answer cited when discussing more crass stunts, like last November’s supposedly true story, “The Fourth Kind” — is that it draws attention, and consequently, sales.

Purporting to be based on actual events, and interspersing supposedly “real” footage with a “dramatization,” “The Fourth Kind” tells the story of an Alaskan doctor abducted by probe-happy aliens. Many of you might remember the screening at Pitt: Milla Jovovich staring somberly into the camera, assuring us the entire film was real.

And it worked, sort of — the “real” footage elicited plenty of screams from the college-educated crowd, and some people I know — I won’t name names — still believed it to be true after they’d left the theater.

Thankfully, my friend saved me from the ruse. As soon as the screening was over, he promised me the whole thing was a hoax. “No one,” he said, “looks as creepy as that ‘real’ person they interviewed.”

Turns out he was right — CNN ran a 2009 article dismissive of the film’s claims, and around the same time, according to The Associated Press, the Alaska Press Club wrung 20,000 dollars out of Universal Pictures after Universal admitted to using fake news archives to publicize their film.

The above scenario is an easy-to-condemn marketing gimmick. But sometimes, as is the case with “Exit Through the Gift Shop,” the deception is artful — the ambiguity enshrouding the movie in a thought-provoking fog. After all, if “Gift Shop” is a hoax, the misclassification underscores one of the film’s central themes: that people will embrace an art without knowing the extent of its artifice.

Still, I’d like to know what species of movie this is — “Exit Through the Gift Shop” is a good — maybe even great — thought-provoking film, but it would remain that way if proof were offered one way or the other.

Maybe I’m nostalgic but I long for the days when audiences didn’t have to fact-check “documentaries” themselves. But until this trickery blows over and “documentary” ceases to become a vague guideline, I, like the rest of consumers, will seek refuge in that infallible bastion of truth: the Internet.