The originals have stood the test of time — the sequels, not so much.
"Look What's Happened to Rosemary's Baby"
Sequel to: Rosemary's Baby
Mia Farrow knew better than to return for Look What's Happened to Rosemary's Baby, so Patty Duke took over the role. The film follows Adrian in his youth and adulthood, because the intentionally vague ending of the original movie apparently left things too open-ended for some.
"The Sting II"
Sequel to: The Sting
While billed as a sequel, The Sting II is more of a reboot, bringing back the original characters with new names and new actors playing them. That doesn't, of course, make it any less superfluous. Paul Newman and Robert Redford get downgraded to Jackie Mason and Mac Davis.
"Staying Alive"
Sequel to: Saturday Night Fever
Because what a disco classic really needs is an '80s sequel. To Staying Alive's credit, John Travolta does return as Tony Manero. Don't get too excited, though. This sequel was written and directed by Sylvester Stallone, but Rocky it is not. Entertainment Weekly called it the Worst Sequel Ever.
"Jaws: The Revenge"
Sequel to: Jaws
Jaws: The Revenge isn't the only Jaws sequel — it's just the worst. It has a staggering 0% rating on Rotten Tomatoes, and it's mostly remembered for the tagline "This time, it's personal." (Yeah, it's personal for the shark.) Also Michael Caine is in this, and that's sad for everyone.