More and more of today's TV humor could be lumped under the heading Comedy of Denial. Zanies and funsters strive to reassure us that not even they think their material is all that amusing. Implicit in the presentation is, "Look, you gotta laugh at something, it might as well be me."

It's part of the David Letterman school of self-knowing hipness but unfortunately, Letterman is one of its very few skillful practitioners. He can be funnier not seeming to be funny than anybody else around. Tonight on Showtime, two comics attempt to mine the same, or a similar, sensibility. One fails resoundingly and the other succeeds impishly.

The failure is Bob Einstein, one-time Smothers Brothers writer, who attempts to parlay a moth-eaten character from Showtime's ugly, defunct "Bizarre" series into a weekly put-on: "The Super Dave Osborne Show," with Einstein as a sort of Evel Shlemievel goofball daredevil. It airs, or rather wires, at 10.

"You're in for a fantastic show," Super Dave assures the audience spoofily. What you're in for are a couple of torturously belabored sight gags momentarily relieved by a Ray Charles song and the exhilarating acrobatic routine of four trampoline-jumping slam-dunkers. They effectively duplicate the classic slapstick basketball game from "The Absent Minded Professor" -- yet without the use of Flubber!!!

As with "Bizarre," Einstein and partner Allan Blye attempt to protract their thin jokes with lavish applications of canned laughter. Seldom in TV history, and this is saying something, has a performer been more generous to himself with synthetic crowd reaction than Einstein is.

The nuts-and-bolts reality of the matter is that Showtime viewers have to pay for this ersatz entertainment, though it's inferior to much of the comedy on free TV. But late in the show, Einstein uses a well-known obscene expression so that people will know they are indeed watching cable. Big thrill.

At 10:30, Rich Hall ambles antidotally along with "The Rich Hall Show," and this cheerful half hour is as inventive and clever as Einstein's is feeble. With his cherubic glint and growly delivery, Hall could almost be the long-lost son of Andy Rooney. Where the comedy of denial can sometimes be merely a rationalization for lousy writing, with Hall it's a statement of modest ambitions engagingly fulfilled.

He begins his program appearing to be the star attraction at a male strip club, but it's the magic of tape editing that puts Hall's head on a beefy torso (his body is played in this scene by Deron McBee, say the credits). A mad chase is precipitated by the removal of Monsieur Hall's bikini underpants. He finds solace in an elaborate Mr. Potato Head disguise that utilizes a chocolate e'clair for a nose.

Soon Hall is at the Mayfair Theater in Santa Monica with a revue consisting of onstage patter, filmed skits, and brief but hilarious heckling from cowriter Ron Richards as an actor specializing in one-man Abe Lincoln performances.

A parody of the PBS staple "This Old House," called "This Old Trailer," finds Hall attempting to install a grand piano in a mobile home -- it can be done -- and fending off a pesky deer addicted to Cheetos. The only weak spot on the show is a sendup of TV evangelists in which they are portrayed by talking change purses. TV evangelists, it would seem, have been spoofed enough.

Hall's shaggy charm recalls such folksy wits as Herb Shriner, and his affinity for Dada-esque visual pranks evokes memories of Ernie Kovacs. He's genuinely droll, and you don't get much drollery these days. Now that he's proven himself on Showtime, he's ready for the big time: HBO!