When you're onto a good formula, why would you let anything get in the way of your delivious cash cow?
Keep on churning out those trailers, even if none of the writers, cast, directors or producers are involved in the follow up.
Surely it can't be that hard to repeat that 'lightning in a bottle' moment for the second time, especially when you have a tried-and-tested formula.
But here are a whole load of sequels that were so bad, they failed to make an impact on popular culture or the box office chart...
19. 8mm 2
Plot: An American diplomat and his fiancé venture into the sordid underworld of sex and pornography in Budapest to find out who is blackmailing them with a video taken of them with a prostitute.
Completely unrelated to the Nicolas Cage movie, it started out with the name The Velvet Side of Hell before Sony bought distribution rights and thought it'd be much more successful to tie in as a sequel of sorts. It wasn't.
18. Marley & Me: The Puppy Years
Plot: This time he speaks! The world's worst dog now has an attitude and a frisky voice. He and his summer pal, Bodi Grogan cause mayhem at the local dog contest. Marley outsmarts lots of other dogs while winning hearts.
Actually a prequel to Marley & Me, a youthful Marley enters a 'puppy championship' with an Australian dog (obviously) and two daft German Shepherds (not with German accents).
17. The Butterfly Effect 2
Plot: Nick Larson is in a car accident with his girlfriend Julie and two best friends, where Nick is the only survivor. A year later a brain tumour allows Nick to change the past by reflecting at photos from his past.
Widely panned for being a rubbish version of the first film, but with an unlikeable main character, it prompted the studios to bring out a third, The Butterfly Effect 3: Revelations, watch the trailer here (but don't blame us if you do)
16. S. Darko
Plot: Donnie Darko's little sister, Samantha Darko, and her best friend Corey are on a country-cross road trip. They find themselves entangled in a dangerous glitch in the time-space continuum.
More time travel, mind-bending stuff from the Darko family as Daveigh Chase, who actually appeared in the original, returns as Donnie's little sister.
S. Darko took some of the more straightforward elements of the original, then added one-dimensional characters and a muddled, disappointing plot.
15. Mean Girls 2
Plot: 17-year-old tomboy Johanna "Jo" Mitchell joins North Shore High School and meets a new generation of 'Plastics'. Jo forms a group of 'Anti-Plastics' to play pranks on the mean girls.
Tina Fey turned down Paramount's offers to write the script on numerous occasions, so they got someone to write a virtually the same, but worse, version of the original.
14. The Scorpion King: Rise of a Warrior
Plot: When young Mathayus witnesses his father's death at the hands of an evil military commander, his quest for vengeance transforms him into the most feared warrior of the ancient world.
Dwayne Johnson turned down an offer to reprise his character, presumably to work on classics like Be Cool and Walking Tall.
If the sequel isn't enough for you, they've made a third film, The Scorpion King 3: Battle for Redemption, with Billy Zane and Dave Bautista, and a fourth, The Scorpion King 4: Quest for Power, starring Lou Ferrigno and Michael Beihn.
13. Carlito's Way: Rise to Power
Plot: In the late 1960s, Puerto Rican Carlito Brigante, the Afro-American Earl and the Italian Rocco are released from prison and become powerful heroin dealers and fierce gangsters.
Based after the first book in the Edwin Torres' series on the criminal life of Carlito Brigante, of which Brian de Palma took the original film's name.
Hostel's Jay Hernandez took over the role of Carlito Brigante from Al Pacino and the film features legendary B-movie star Mario Van Peebles - so it must be a corker.
12. Bachelor Party 2: The Last Temptation
Plot: Melinda loves her fiancé Ron, but her brother Todd, doesn't approve of his upcoming brother-in-law. He wants Melinda to cancel the wedding, but for her to do that, he must get Ron to mess up. He hopes to achieve his plan by organizing the world's wildest bachelor party.
Originally intended to be a remake of the 1984 Tom Hanks comedy, the biblical-sounding Bachelor Party 2: The Last Temptation turned into a sequel.
The storyline is rubbish and the jokes never hit their mark, making the female topless scenes the only watchable thing about this movie.
11. Road House 2: Last Call
Plot: DEA agent Shane Tanner, the son of a legendary cooler named Dalton, moves to Louisiana to fight a drug dealer named 'Wild Bill' who is using violence to force Shane's uncle to sell his bar the Black Pelican - a perfect location for drug smuggling.
Originally the uncle was supposed to be James Dalton from the original played by Patrick Swayze, but the character was changed after he turned down the project. Probably because he could see how it would turn out.
10. Tooth Fairy 2
Plot: Larry Guthrie loses his first love to the town hot shot; he tries to win her back by volunteering at her after school program. But when Larry accidentally tells the kids that the tooth fairy is make believe, he is soon transformed into a tutu clad fairy with a sentence of collecting teeth.
Dwayne Johnson didn't return for this one either and was replaced with blue-collar stand-up character Larry The Cable Guy - it wasn't a great replacement, and it wasn't a great film.
9. Lost Boys: The Tribe
Plot: Former surfer Chris Emerson and his sister Nicole move to Luna Bay for a new life. At a party Nicole becomes a half-vampire and local vampire hunter Edgar Frog advises that she drank vampire's blood and can only be saved if the head-vampire is killed.
'The Coreys' - Corey Haim and Corey Feldman returned as the Frog brothers, while Keifer's half-brother Angus Sutherland also featured.
Despite being hated by critics because it was crap, it was Warner Premiere's highest selling DVD release of 2008. It covered its $5 million production cost in its first three weeks of release.
Because of its runaway success on DVD, another sequel, Lost Boys: The Thirst was made, which didn't do as well.
8. The Haunting in Connecticut 2: Ghosts of Georgia
Plot: A young family moves into a historic home in Georgia, only to learn they are not the house's only inhabitants. Soon they find themselves in the presence of a secret rising from underground and threatening to bring down anyone in its path.
Georgia, renowned for not being anywhere near Connecticut was the location of the second Haunting in Connecticut film, which had no relation to the original, except for the hopes that a similar name would be a box office draw.
There was talk of a The Haunting in New York film, but everyone agreed that it had gotten ridiculous by that point.
7. I'll Always Know What You Did Last Summer
Plot: A group of teenagers in Colorado find themselves being stalked and killed one by one by a mysterious figure with a hook, exactly one year after they covered up a friend's accidental death.
Originally planned to have Jennifer Love Hewitt and Freddie Prinze Jr. returning, but the movie lay around for a couple of years and they'd decided not to waste their time, so a new script was written.
Oh yeah, and the hook-wielding villain is Ben Willis, the decomposed victim from the first film, but he's supernatural and can teleport. So yeah.
6. Legally Blondes
Plot: Moving from England to California, the youngest cousins of Elle Woods must defend themselves when their schools reigning forces turn on the girls and try to frame them for a crime.
Following Legally Blonde 2: Red, White & Blonde, Legally Blondes dispensed with Reese Witherspoon and brought us twins Camilla and Rebecca Rosso from Wimbledon.
Replacing an actual court with a student court and having two blonde twins didn't prove double the fun.
5. The Rage: Carrie 2
Plot: A massacre strikes up after an outcast girl is taunted by a group of high school jocks, all of them unaware of her violent, cutthroat psychic power.
The 1999 sequel to the 1976 horror classic involving Carrie's half-sister, who goes through a strikingly similar bullying and humiliation campaign.
When it was released, it made $17m from the $21m production budget but it was considered 'not that bad' by most, but still managed to underwhelm everyone that saw it.
4. Cruel Intentions 2
Plot: Taking place several years before Cruel Intentions, back to when Kathryn first meets Sebastian, their sexual attraction to each other and their enjoyment in destroying the lives of their peers.
Originally a TV series based on the first film titled Manchester Prep - it was scheduled to premiere on Fox, but the show was cancelled by a reportedly outraged Fox chairman Rupert Murdoch.
The plot was reworked into prequel Cruel Intentions 2, starring a young Amy Adams playing an even younger version of Sarah Michelle Gellar's character.
If you liked the look of it, fear not, a third Cruel Intentions film was made, and the trailer can be watched here.
3. American Psycho II: All American Girl
Plot: Rachael Newman developed an interest for murders after she encountered psychopath Patrick Bateman. She enrols at the university department for Behavioural and Social Sciences to get a job at the FBI and won't anything or anyone get in her way.
A young Mila Kunis couldn't make this a respectable film - even with the help/hindrance of William Shatner - which wasn't supposed to be an American Psycho film at all and was adapted from a script titled The Girl Who Wouldn't Die.
Mila Kunis has admitted that she's ashamed of the direct-to-DVD film.
2. Hollow Man II
Plot: A Seattle detective and a biologist find themselves the targets of murder from an invisible assassin gone rogue, as well as the government forces who caused him to become invisible.
Christian Slater stars in this sequel which was based on the script was based on the very first draft of the Paul Verhoven's original - and shows why most films aren't made from their original scripts.
1. Ace Ventura: Pet Detective Jr.
Plot: The son of an eccentric detective steps into his father's shoes after his mother is wrongly arrested for stealing a baby panda.
What do you do when Jim Carrey vows never to do a sequel (let alone a threequel) for his career?
Replace him with a not funny chubby kid to ape of all his mannerisms and catchphrases, yeah that'll work.
Thing is though, it didn't work and the direct to video spin off sequel was terrible. Kids might have enjoyed it though.