I watched the worst film i've seen in a long while earlier this week - 10,000BC.
Truly atrocious from start to finish - script, acting, plot, editing, and effects were all woeful. Ironically, it's a sparkling Blu-ray release, with superb picture (which just shows up the dodgy effects) and corking HD sound. Thankfully I only rented it from LoveFilm...
Previous to that, I think Guy Ritchie and Madonna are the couple with the worst film credentials between them. Once Matthew Vaughan left the Ritchie/Vaughan field (after Lock Stock and Snatch) I think it's clear to see where the talent lay...
So, Swept Away and Revolver have to be contenders for worst film - I didn't finish watching either.
Eyes Wide Shut would be on my list, too...
Clare Newsome is Editor-in-Chief of What Hi-fi? Sound and Vision