They are the movies audiences love for all the wrong reasons - the cinematic flops that are now finding appreciative audiences at cult screenings.
Once, these films were slaughtered by critics; now, they are attracting viewers who laugh, heckle and applaud at late-night sessions and "worst movie" festivals.
While serious film buffs have long argued whether Citizen Kane or a dozen other classics is the greatest movie ever made, digital cinemas with adventurous programmers are inspiring interest in the other end of the movie spectrum - the Citizen Kanes of awful.
Fans are discovering the likes of Tommy Wiseau's 2003 romantic drama The Room, which has the writer-director-producer-financier playing a banker who is betrayed by all his friends. A "landmark in ineptitude", wrote one critic about its confusing plotlines and continuity errors; others were less kind.
Then there is Claudio Fragasso's Troll 2, a 1990 horror film about a family pursued by vegetarian goblins who want to turn them into plants. "Very, very bad," noted a reviewer, "and there are no trolls." It ranks last on the popular Internet Movie Database's bottom 100 films, below even such recent shockers as Battlefield Earth and Gigli. And not forgetting James Nguyen's Birdemic: Shock and Terror, a low-rent Hitchcock homage from 2008 that has some apparently very unconvincing birds attacking a small town.
They are contenders with Ed Wood's 1959 sci-fi film Plan 9 from Outer Space for the title of most ineptly directed, least convincing, laughably awful movie ever made, although some consider his semi-autobiographical effort about transvestism, 1953's Glen or Glenda, to be even worse.
Once, it took decades for so-bad-they're-good movies like these to become cult favourites.
American cable TV movie Sharknado, from the producers of such strangely familiar-sounding films as Transmorphers, Snakes on a Train and Lord of the Elves, has become such a cult hit in eight weeks that it is heading to cinemas next month.
Sharknado is a horror-sci-fi film about a hurricane that dumps bloodthirsty sharks into Los Angeles, with a cheesy plot, unconvincing visual effects and sub-soapie acting.
But while Sharknado was purposely made as a trashy B-grade movie, film and digital arts lecturer and filmmaker Stefan Popescu believes the real classics take themselves much more seriously.
"There's a certain qualifier for best worst movies - an earnestness," he said. "You have to step into filmmaking really innocently and think that you're making the best film that anyone has ever made, then it's a complete failure - and you can't see that it's a failure."
Popescu said fans of tragically awful movies - largely under 40, with a healthy Gen X cynicism - enjoy watching them as a community. "You can watch these movies online quite easily but you don't have that communal mocking of bad moments."
Some screenings come with bingo cards, with fans crossing off infamous lines of dialogue or scenes as they crop up to win prizes.
"It adds a little bit more interactivity," Popescu said.
At late-night screenings of The Room in Los Angeles, fans are even more interactive. Just as at screenings of The Rocky Horror Picture Show and The Big Lebowski in Australia, they dress up as their favourite characters and join in with the dialogue. And in references to baffling moments on screen, they also toss footballs and throw plastic spoons.
Jose Maturana, who runs cult movie marathons and drive-in nights through Melbourne's Valhalla Social Cinema, joined a packed house at Cinema Nova recently for the "cultastrophe" double bill of Sharknado and Frankenstein's Army, a horror/sci-fi film about a secret Nazi lab that stitches together super soldiers from dead bodies, which he calls "a big WTF kind of film".
"They were there in force and ready to laugh," he said. "You walk out and think, 'That's why cult film is so great sometimes'.
"The surprise isn't in the quality of the film - it's in the reaction and the company you keep at the time."
Certain films, Maturana said, are "like a time capsule of hairstyles, production design and dialogue" of another era.
"When you're watching them, you're thinking, 'How on earth was anyone ever convinced that this was going to work?' But I love the fact that it exists."
Alex Temesvari, who runs I Heart Retro screenings at Sydney's Hayden Orpheum, drew an enthusiastic audience for a Worst Film Festival recently that featured Plan 9 from Outer Space, Glen or Glenda and Robot Monster.
"There are movies that are so bad that after 20 minutes you think I just can't watch another second," he said. "Then there are movies that are so hilariously bad, you're glued to the screen. It's a real fine line."
Temesvari said ticket sales "are going through the roof" for The Room in October. "It's a real vanity project," he said. "[Wiseau] is completely earnest about this thing, yet the end result is one of the most atrocious pieces of film ever released."