I go by a 10 point scale that looks something like this:

10 - Masterpiece

9 - Great movie

8 - Good movie

7 - Enjoyable enough

6 - It was okay, but I probably wouldn't watch it again

5 - At least I didn't pay to see it...

4 - This was pretty bad. But at least there was full frontal nudity in it.

3 - There is nothing redeemable about this movie.

2 - I hate this movie and hope that it gets removed from history.

1 - Chairman of the Board