“Exit Through the Gift Shop,” one of this year’s Oscar nominees for Best Documentary, is… “Exit Through the Gift Shop,” one of this year’s Oscar nominees for Best Documentary, is an excellent film, rife with humor, colorful characters and incisive commentary. There’s just one problem: Many people thought it was all a hoax.

In fact, many people thought half of last year’s “documentaries” were closeted dramas — scripted theatrics dressed up as journalism. From the bemusing “I’m Still Here” to the enthralling “Catfish,” the 2010 film community was continually mired in puzzling out which movies were factual and which movies were, to borrow a phrase from The New York Times, “prankumentaries.”

Accordingly, I’ve conceived of a new Oscar title: “Best Ostensible Documentary.” This is the award to bestow on films audiences were told were true, yet aroused an alarming degree of critical skepticism. So, without further ado, the best — or most notorious — ostensible documentaries of 2010 are …

“Exit Through the Gift Shop”: As press materials tell it, “Exit” is the story of Thierry Guetta, an ebullient, dunderheaded Frenchman whose unlikely rapport with street artists lead him to Banksy, the reclusive, high-profile British prankster. Somewhat remarkably, the two men become friends. But when Guetta decides to become a street artist himself, christening himself Mr. Brainwash and mass-producing a vapid series of Warhol knock-offs, Banksy feels obligated to endorse him. Unsettlingly enough, the endorsement and the subsequent attention he receives from LA Weekly, is virtually all Guetta needs to climb to the forefront of the Los Angeles art scene. His opening exhibition attracts a large, eager crowd.

If this film were true, it would be a revealing portrait of street artists and their admirers. But many critics are convinced the whole thing is a sham. For one thing, it would be entirely in character for Banksy to make a documentary about a ruse he played on the art world that was itself a ruse on the art world. More importantly, perhaps, Mr. Brainwash seems too comically oblivious to be real.

Nevertheless, “Exit Through the Gift Shop” has yet to be conclusively disproven — hence the Oscar nomination. In both instances, it’s a stimulating, subversive examination of the hype that sometimes makes artists famous in spite of their artwork.

“I’m Still Here”: Sadly, the grotesque “I’m Still Here” lacks the intellectual backbone that landed “Exit” on several “year’s best” lists. Originally billed as a documentary about the trials of an unkempt, dimwitted Joaquin Phoenix who opts out of acting for a career in hip-hop, the film is perhaps best described as a two-hour montage of failure: Phoenix rants obsessively, does drugs, orders hookers, has his album rejected by Diddy and, most unnecessarily, has his face defecated on.

At its best “I’m Still Here” gestures at a rumination on celebrity identity, and how the famous are devoured in the age of YouTube. Mostly, however, Phoenix’s deterioration seems self-imposed and moreover, wholly without precedent.

Further diminishing the impact of “I’m Still Here” is the fact that it’s the only admitted mockumentary on this list. What inspired Phoenix and director Casey Affleck to carry out such an elaborate stunt remains unclear. Ultimately I was almost too underwhelmed to care.

“Catfish”: Fittingly, the third film that piqued critics’ skepticism this year was in some ways an expose of Facebook — an online arena where truth becomes warped beyond recognition. The story goes as follows: A photographer begins receiving remarkably vivid paintings from an 8-year-old named Abby. Impressed, he befriends her and subsequently her entire family on Facebook. Inevitably, he develops an attraction to Abby’s older sister, whose profile suggests a tall, attractive blonde with a burgeoning talent for guitar. As is always the case with such relationships, online correspondence soon seems inadequate, and the photographer and his filmmaker friends set out to find the family. Needless to say, all is not what it seems.

Without giving up any spoilers, many commentators have faulted the filmmakers for exploiting their subjects, and being willfully credulous of certain transparent illusions. Others, like documentarian Morgan Spurlock and comedian Zach Galifianakis, have proclaimed the film an outright hoax. Like “Exit Through the Gift Shop,” however, “Catfish’s” resonance is hardly diminished by these accusations — on the contrary, the fog of truth only renders it more intriguing.

And the winner is …

“Exit Through the Gift Shop”: Of course, the only film on this list that would benefit tenfold from being exposed as a hoax. As a straight documentary, it’s amusing. As a faux-documentary, it’s a fascinating exercise in metafiction. Of course that’s just my opinion — in criticism, as in cinema, objective truth is hard to come by.