Does anybody remember Delirious, with John Candy? Only movie I ever wanted to walk out on (and would have if my date hadn’t picked it and I’d owned a backbone at the time). That movie had enough suckitude to qualify as a black hole.
Smilla’s Sense of Snow
Man was that film pointless. Has Julia Ormond’s career ever recovered from that trash? I wanted to walk out on that movie, but I was 37,000 feet over the Pacific Ocean.
The all-time winner for me is still Glen or Glenda?, perhaps Ed Wood’s most heartfelt film.
Imagine a boring movie about transvestites. Now imagine that movie with scenes of stampeding buffalo while Bela Lugosi shrieks, “Pull the string!” That, my friends, is Glen or Glenda?.
There there. It’ll get better. One day at a time. 
I don’t know why I even decided to watch Repossessed, the Leslie Nielsen and Linda Blair movie which is a parody of The Exorcist, a movie that’s parodied so much that it’s almost become a cliche. I felt embarassed for Blair, that’s how much I hate this movie. I saw it on Comedy Central a few years ago, when they kept showing the movie 24 hours a day (almost).
After seeing Ed Wood, I wanted to see if his stuff really was all that bad and watched Glen or Glenda, Bride of the Monster, and Plan 9 from Outer Space. But for academic exercise, these films are, simply, unwatchable.
The Color of Night
Lost in Space
The two worst movies I ever paid to see. Hands down. I want my money and four hours of my life back.
Worst movie I ever saw on cable was No Retreat, No Surrender 2. I have nobody to blame but myself for watching that one, though.
I enjoy vampire movies, so even if one is just “OK” I’ll probably like it. From Dusk Till Dawn, John Carpenter’s Vampires (and even the sequel with Bon Jovi), Dracula 2000–I like them all. So a while back my friend and I see a commercial for a vampire movie called “The Forsaken” and we go to see it.
OH MAN IT WAS AWFUL!!!
The vampires didn’t even appear to have any special powers! There were absolutely no special effects or even MAKE-UP for crying out loud! Seriously! These vampires didn’t even have FANGS!
And the “story” was just boring and stupid. Not any plot really–just “we got to get away from these vampires, but our car’s broken down. Dang.”
Utter crap.
Recently? As in the past few years?
Altman’s Dr. T and the Women with Richard Gere and a whole bunch of talented actresses. Despite Farrah nude in a mall fountain, The Wife owed me three films after that one. She found it pointless as well.
All time bad film that I have not yet deleted from my permanent memory would be Basketcase, the heartwarming story of a boy going to the Big City with his deformed conjoined twin brother (in the titular basket), seeking revenge on the veterinarians who seperated them. Damn, but that one was a stinker.
I know I have spent good money on many bad films, I have just been lucky enough to block the memories of most of them.
Cube 
The setting never changes, except for the color of the walls. And the ending just makes you want to throw the tv out a 10 story window.
The Shooting Party. Literature transmuted to Boredom.
Sphere. Can’t remember much about it. I recall popcorn.
Grand Canyon. Recommended to me. Meaningful. Cures insomnia.
Belle de Jour. “Full of surprises.” Yeah. Surprisingly stupid.
The Austrailian film “The Castle” possibly one of the worse films I have ever seen.
Lifeforce. Everyone just shook their heads leaving the theater.
Actually, I loved both “The Man Who Fell To Earth” and “Night Of The Comet,” so keep that in mind when I tell you the worst movies I’ve ever seen are (and I can only remember the names of a few):
Problem Child - The one where John Ritter adopts a nasty little boy. I believe this was supposed to be a comedy and it was absolutely one of the most mean spirited pointless things I’ve ever seen.
The one with Michael Keaton where he plays a mental patient, who, with some other mental patients, either escapes or gets abandoned somewhere. It sucked so badly I truly can remember no more than this.
Batman, also with Michael Keaton.
Dude, Where’s My Car? Dear gawd, will it ever end?
The one where the stdents in the school are being invaded with aliens, and there’s something to do with snorting caffeine in it.
Robin Hood with Kevin Costner.
I’ll think of more, I’m sure.
Gotta agree on Sphere. Good book, baaaaaaaaaaaaaad movie.
But my favorite actor Samuel L. Jackson was in it, so it wasn’t all bad. Whenever he was on screen I could plug my ears and pretend I was watching a good movie.
That insufferable, interminable chick flick with Julia Roberts as some movie star slumming in London and Hugh Grant (who is both insufferable and interminable in his own right) as a humble and unassuming book seller.
I don’t go to the movies very much. My second choice is Gene Autrey and the Underground City, an early 1950’s serial. Smiley Burnett was in it though.
Easy enough - I keep a list on www.imdb.com. I rnaked all of these a 1 on a scale of 1 to 10:
¡Three Amigos!
The 'burbs
*batteries not included
10 Violent Women
Ace Ventura: Pet Detective
The Adventures of Ford Fairlane
Blues Brothers 2000
Body of Evidence
The Brady Bunch Movie
Clue
Dead Men Don’t Wear Plaid
Doc Hollywood
Doctor Detroit
Dumb & Dumber
Eddie and the Cruisers II: Eddie Lives!
Fatso
The Flintstones
Grease 2
Greystoke: The Legend of Tarzan, Lord of the Apes
Grumpy Old Men
Home Alone 2: Lost in New York
Ishtar
Jaws 3-D
Look Who’s Talking Too
The Man with Two Brains
Mannequin
Mannequin 2: On the Move
Police Academy 2: Their First Assignment
Police Academy 3: Back in Training
Police Academy 4: Citizens on Patrol
Police Academy 5: Assignment: Miami Beach
Police Academy 6: City Under Siege
Police Academy: Mission to Moscow
Popeye
Porky’s
Runaway Bride
Scrooged
Sgt. Pepper’s Lonely Hearts Club Band
She’s All That
Shining Through
Soul Man
Stop! Or My Mom Will Shoot
Superman III
Tango & Cash
Toys
Oh yeah, I almost forgot Woo. Fortunately, that was one of the few movies that I did manage to walk out on, so I didn’t have to suffer too much.
Jada Pinkett was supposed to be a cute, free-spirited girl, but she just came across as a cute, mean-spirited bitch.
Battlefield Earth, without a doubt. And more recently:
The Hours.
Dr. Terror’s Gallery of Horrors (not to be confused with the pretty good Dr. Terror’s House of Horrors, an unrelated flick) - I saw this under the title Tales from the Past, which the IMDB doesn’t seem to know:
http://us.imdb.com/Title?0062193
John Carradine and Lon Chaney Jr. in an anthology piece with the worst plots and acting you’ve ever seen. It reads as if your friend’s seven year old brother wrote his own horror movie after overdosing on Creepy and Eerie magazines. The best parts are the scenes they literally stole from Roger Corman’s The Raven (I don’t mean they reshot them – they have the actual shots from Corman’s film). Amazingly bad.
The Astrozombies – John Carradine, again, in a Ted V. Mikels film. Even the presence of Tura Satana as femme fatale can’t save this one:
http://us.imdb.com/Title?0064048
Curucu, Beast of the Amazon – Curt Siodmak wrote.directed! Beverly Garland starred! In color and shot in Brazil! Yet it’s incredibly dull, boring, and awful, and the ending is absurd. The reviewer on the IMDB and I had the same experience – heck, we may have watched the same showing:
http://us.imdb.com/Title?0049115
The Terrornauts – screenplay by John Brunner(!), based on a novel by Murray Leinster[!!) How could it turn out so bad. The movie poster, if you can find it, is a scream – it doesn’t depict anything that actually happens in the movie.