Caligula

Bob Guccione, Tinto Brass, Giancarlo Liu, 1979 (1*)
One would think that filming the story of a Roman emperor more decadent than all the rest would at least make for interesting viewing, but.. This film was so bad that it took three directors to achieve it, including the founder of Penthouse magazine, Bob Guccione. I believe this film caused the invention of the Vomitorium.

I was fooled into seeing this in the theater by the cast, which starred Malcolm McDowell, Peter O'Toole, John Gielgud, and Helen Mirren. In spite of the nudity and sex, none of them has been in a more unwatchable film. And they made a "four-disc imperial edition"? Good grief.. you have to be kidding.

I also found the PBS series I, Claudius to be unwatchable - perhaps I'm baised against films about imperialistic, republican forms of government that sends their armies into any other nations they can reach, claiming to bring a higher standard of living and democracy to peasants, and to allow religious freedom.

Spaceballs

Mel Brooks, 1987 (1*)
All you really need to see are the photos of Rick Moranis as Dark Helmet, and John Candy as Barf, and you can tell this is one lame parody of Star Wars. Add to the cast Mel Brooks as Yogurt, and stalwart actors such as Dick Van Patten and Joan Rivers, and throw in some of the cheesiest special effects ever and you have perhaps the worst comedy ever attempted. Not even six year olds will find this amusing. Avoid like the plague. and no: it's not "so bad that it's good" - it's so bad that you'll wish you had the 15 minutes or so back that you waste on this before rushing off to have a root canal without novocaine to remove the memory.

There are good Mel Brooks films, though not many, as he's almost the most overrated comedy director of all time, if you go with 'batting average'. Stick with The Producers and Young Frankenstein