Easy: With few exceptions (such as the Frank Langella version of Dracula, which was great), any re-make of a classic flick. The Thomas Crown Affair comes to mind - after the classic version with Steve McQueen and Faye Dunaway, the later version with Pierce Brosnan was a joke. (I would probably say the same thing about the new Ocean's 11, although I haven't seen it yet.) Ditto the re-make of Psycho, which was a rip-off of the Hitchcock original, right down to the camera shots. Ditto Never Say Never Again, which was a rip-off of the original Thunderball.

And two musicals come to mind: Mame (featuring the then 190-yea-old Lucille Ball, it could never compare with the original, non-musical version with Rosalind Russell, which is a cult classic) and Lost Horizon (a joke of a film with some of Burt Bacarach's worst songs ever - he should have stuck to writing for Dionne Warwick).