I guess I'm very lenient with my picks, but there are a few CB movies that get a lot of crap that I enjoy:
Fantastic 4: Rise of the Silver Surfer
Ghost Rider: Spirit of Vengeance
Iron Man 2
I don't think any of them are classics by any means, but I think all 5 are ok time-wasters, entertaining enough films.
As far as awful CB films, I have to go with Superman 3. This is a film I just have a hard time getting through. The GREAT Richard Pryor is completely wasted, as is Chris Reeve and Robert Vaughn. The only redeeming feature is Pamela Stephenson. She was a hottie!