what is the style of art work called that Ed Roth uses to create Rat Fink?

Answer 1

My opinion is that "Big Daddy" Roth created his own, unique genre with his illustrations.

It is, essentially, just his style of cartooning, no more a particular style than Berke Brethed's in Bloom County, Charles Schultze's in Peanuts, or any other cartoonist's style.