A lot of fun
I definitely wouldn't classify this as "so bad it's good." It's cheap, yes, and very silly. But what do you want from a movie called The Green Slime? Unlike many of these 50s scifi movies, it actually moves along at a fast pace, which is exciting and refreshing. I'm gonna give it a 9/10, because I think it's one of the best movies of its kind.
What's the Spanish for drunken bum?