Trash Can: Is a movie so bad it's destined to be either destroyed underfoot or burned. The lowest rating.

Wretched: A movie with no redeeeming factors that's just a hop away from the getting the big Trash Can.
Below average: Pretty bad, but sometimes there's a few moments that aren't bad. Skippable at best.
Average: Passable fare that's usually okay viewing but isn't very inspiring.
Good: Usually an entertaining movie with enough decent things about it to recommend.
Very Good: A step above "Good" be it in "cool" factor, creation or entertainment.
Great: About as close to perfect as you can get, but not quite enough to be the top of the heap.
Excellent: The peak of horror movie making.