"The Screaming Skull" IS NOT A BAD MOVIE!
"Mystery Science Theater 3000" is not the ultimate judge of a film's worth. Making fun of the film is one thing, but, if they thought this movie was actually bad, they don't know very much at all about film. I'm certain, if you were able to ask them, they'd tell you that, based solely on the level of "cinema" in the film, this is either the best movie they've ever shown or one of the best. (Hey, they mentioned Renoir's "Rules of the Game," so they clearly have some knowledge of real film, unlike you cretins.)
Here's the thing: You people have absolutely zero notion of the concepts of 1) "Suspension of Disbelief" and 2) "Filmmaking." If you could wrap your mind around either of these ideas, you'd be able to tell that this movie is, at the very least, effectively made. The cinematography was top-notch, I felt, and the direction was somewhere north of fair.
(And, by the way, "suspension of disbelief" does not mean simply "buying" everything the filmmakers show you, as many people have taken that phrase to mean. It means that you accept that what you are watching is a movie and thus has certain limitations, but, more importantly, that you try you forget that it's a movie and allow yourself to be affected by the music, atmosphere, etc. Basically, in direct opposition to the ultimately judgmental, condescending stance most people take to all movies in general and older horror films in particular.)