Troll 2 is the product of Claudio Fragasso and Rosella Drudi, Italian filmmakers who hid behind aliases and limited English skills while shooting — nay, getting away with — Troll 2 in Utah in 1989. The film follows a family’s vacation gone horribly wrong — unaware their destination of Nilbog (read it backwards) has been overrun by vegetarian creatures not above converting flesh to flora.

It also features a dead grandpa handy with Molotov Cocktails, weaponized popcorn, amusing assumptions of homosexuality, a dance sequence from a teen in a Garfield T-shirt, magical bologna sandwiches, urine-soaked food and the greatest castration threat ever written.

Troll 2 didn’t simply squeeze through a language barrier, it vaulted a barbed-wire fence erected between every instinct or interpretive skill one traditionally brings to a film. Wikipedia’s most amusing understatement ever: “Troll 2 is widely considered to be of poor quality.”

The same can’t be written of Best Worst Movie, a terrific documentary about Troll 2’s unexpected resurgence, the unlikely path to its existence and the timeless question to bad-movie lovers everywhere: What is the standard of “bad,” exactly?

In ways as cinematically philosophical and personally poignant as they are riotously funny, Best Worst Movie asserts that entertaining ineptitude like Troll 2 always trumps depressingly dispassionate dreck like Daddy Day Camp (which one Troll 2 screening happily preempts).

Michael Stephenson — the freckle-faced boy who pissed on his family’s dinner to save them in Troll 2 — directed this documentary, whose ostensible star is George Hardy.

Now a do-gooder dentist in small-town Alabama, Hardy practiced in Salt Lake City in the late 1980s. On a whim, Hardy responded to a casting call for an area film — a whimsical throwback to days as a drama star and cheerleader. Hardy got the lead, but couldn’t prepare for the insanity.

Aggressively gregarious like a real-life Buddy Garrity, Hardy’s spastic tactics make it hard to believe he starred in any movie not filmed in someone’s backyard. Well, Troll 2 is only a tiptoe above that. Hardy’s supporting cast is as random as could be, including a mental patient out on a day pass and so high he had no idea what was transpiring.

In a last-ditch bid for visibility, Fragasso desperately latched onto 1986’s Troll — a film with a character named Harry Potter Jr. (no relation) and in which Sonny Bono grotesquely transforms into a turdish plant, but that shares no narrative continuity whatsoever with Troll 2.

Over time, Hardy concentrated on dentistry and consigned Troll 2 to his past. But one day, someone asked about it, having seen it on TV, and Hardy began poking around on the Internet. (Strangely, Stephenson strangely never seeks out those who willingly programmed this thing.)

Internet Movie Database users named Troll 2 the worst movie ever made. Its Rotten Tomatoes ranking is firmly ensconced at zero percent. But Troll 2 had been embraced by everyone from improv groups to American soldiers, spawning midnight screenings and a cottage industry of tie-in crapitude — 8-bit video games, Guitar Hero Easter eggs and white-teen rap odes that sound like Ween sipping from industrial-sized jugs of cough syrup.

Thus, Hardy and Stephenson find that in city after city, at sellout after sellout, Troll 2 has endeared itself to ironically appreciative audiences — arguably the last bastion of cult cinema discovered through WTF word of mouth and not demystified by the Internet’s spoiler minefield.

Gathering Fragasso and their far-flung co-stars to join them, Hardy and Stephenson elicit strange, occasionally stinging truths from people with no pretense, or real claim, to popularity.

Don’t tell that to Hardy, who begins calling himself a “cult luminary” (in a limelight he’s got to shake and slap around to make shine) and clasps to the fraying strings of fringe fame. In Troll 2’s context, his signature line remains great. Repeated ad nauseum in Worst, “You can’t piss on hospitality! I won’t allow it!” becomes a plea whose pathetic nature even Hardy acknowledges.

Hardy’s perpetual complaisance generates hearty comedy, but also concern for whether he’ll sacrifice a good life to coast on Troll 2’s fumes. One horror-convention scene takes The Wrestler’s grubby claustrophobia of wash-ups signing autographs into the real world — emphasizing the utilitarian nature of “performances” in the horror genre. There, Hardy decides whether Troll 2 will be a great story to tell or a foolish reason to uproot himself.

Troll 2’s other actors can’t deflect Internet-flame criticism about their performances with luxury or fame, either. They’re everyday folks living in small spaces with hoarded junk littered about or, in co-star Margo Prey’s case, living with infirm mothers for whom they’ve abandoned everything (including mental fitness) to care.

To them, agents and auditions are as foreign as Fragasso’s spiel. A primadonna calling his actors “dogs,” Fragasso views Troll 2 as an overlooked analysis of American families and a parable promoting togetherness as a triumphant tool over … well … being eaten by vegetarian goblins.

Still making Italian films, Fragasso comes off as an egotistical ass. When Prey compares Troll 2’s more “talkative” tone to Casablanca … well, that’s bonkers, too. But it’s commendable because she truly believes this group of oddballs did their best. The Internet can judge them, but Worst gives no reason to doubt them — an A for crazily misguided effort two decades later.

The film ends with a threat of Troll 2, Part 2. If that should never come to pass, it’s guaranteed to be arch, insincere and forced — everything that Best Worst Movie and, for that matter, Troll 2, is not.

The biggest knock on Worst’s DVD release? It’s not bundled with Troll 2 itself, which, like Coven to American Movie, must be seen in full to be appreciated.

Still, there are almost three hours of bonus material included, including 91 minutes of deleted scenes (the best ones further deflating Hardy’s convention-circuit delusions) and interviews, as well as fan tributes, almost all fatally self-consciousness the way Worst and Troll 2 aren’t.