I would like to make clear that I do not care for Sealab. I don't like superheroes or comic books. I do like a lot of Adult Swim and other animated shows.
It starts as a tepid spoof on supervillain doomsday plots with villain Killface running into budget constraints and mundane obstacles to destroying the planet. At some point you notice Killface and Xander Crews, his supposed arch nemesis, are chatting in a swamp on an ill-fated duck hunt and you wonder how it got here. The dialogue is so bizarre and hilarious, peppered with running jokes and lines that are as hard to explain as the face-stretching laughter they cause.
Most impressive is the way the show has episode-to-episode continuity without sacrificing any of the comedy.