Nah, official art has never had her lacking pants. Even in the Kalecgos manga where she looked like a Night Elf in style, she had pants (though they drew her with a REALLY weird chest armor).
Fanart, however, usually never fails to have the crotch plate only.
The only thing that could be made more fluid (heh) about Morphling is his bottom half. Would like to stop seeing that peg that's supposed to just be flowing water. Hopefully without adding too many particles that crash my game.
YAS! I'm so glad other people remember that ancient Cartoon Network commercial. Every time I see Solomon Grundy in anything now that's the first thing I think of.