I've watched so many shit movies i can't remember; where do i begin? Let me see, one just on the top of my head - HellBoy; waste of my 3 hours and due to me naivety i actually continued watching, thinking it'll get better! Shame on me to have faith in such a ridiculous piece of scrap
I haven't seen Gigli, and don't plan to based on the score on IMDb. However, the worst movie that I have ever seen would have to be Glitter(2001), as you mentioned in your OP. Yeah, very bad.
There was a film called 'Valentine' on the other night. Deserves a mention.
As does the remake of 'Carrie'. Although to be fair I haven't seen the original.