Having worked in a Movie store (Mr. Movies) in the mid-1990's, I was privileged to see some truly awful movies come through at that time. Will have to collect my thoughts for a proper answer...
But I will say that the art of the so-bad-it's-good movie is really an artfully fine balancing act. It should be praised to the heavens whenever it is achieved.
In that category, the movie
They Live comes to mind, and mostly due to the *awkwardly* long fight scene between Keith David and WWF's 'Rowdy' Roddy Piper.
https://www.youtube.com/watch?v=-mm4mLsCAyI
Just wear the dang glasses, Keith!!