more to come on this but:
I'm reading Michael Barrier's "Hollywood Cartoons," book, and although there's a lot of opinion injected that i disagree with, there a ton of useful tidbits too!
Apparently [according to Barrier via interviews with Clampett] Rod Scribner was pretty influenced by George Lichtenstein, above. Mainly his "Grin and Bear it," comics. He looked to stylistically duplicate the looseness of Lichty's comics in his animation in the 40's. After discussing this with Clampett, he'd get the go ahead to "Lichty it up," and do his really loose animtion. At times he'd use a brush, or ink, etc.
Scribner's a big influence for me so when I find out about where he pulled from I get excited.