Vomit, nose-picking, belches, gerbil-filled underpantsdoes Chevy Chase have your attention yet? Using at various times every one of these time-honored devices in search of a decent cheap laugh, The Chevy Chase Show (Fox, weeknights; check local listings) has managed only to give vulgarity a bad name. Sure, everybody dumped on Chase's Sept. 7 premiere fiasco, highlighted by the host's smirk-a-rama boogaloo with Goldie ''This is my backside'' Hawn. But to truly understand the tedium Chase has achieved, you have to catch him these days, now that the show has settled into a mind-deadening, Chevy-centric rut.
During his second week on the air, his interviewing style had been honed to this conversation stopper directed at guest Dennis Hopper: ''I'm actually a very good golfer.'' Chase also had the gall to rerun a taped comedy bit he'd aired in the first week of his show. Perhaps sensing the host's blithe contempt for them, the audience that fills Hollywood's new Chevy Chase Theatre has steadily turned into the worst-behaved crowd in late-night television; they hoot and yell and cheer over whatever pitiful chatter Chase is attempting to wring out of a luckless guest.
Just about the only thing the Chase Show has over the other new entry into the talk-show wars, Late Night with Conan O'Brien (NBC, weeknights, 12:35-1:35 a.m.), is that at least Chevy doesn't have a smiley sidekick weighing down his couch. Owner of the bounciest forelock in show business, Conan O'Brien has since his Sept. 13 premiere succeeded in establishing himself as an intelligent, likable fellow who really shouldn't be allowed to dance along to his own theme music. But I'm afraid his buddy Andy Richter is a real liability: Ploddingly spoofing Ed McMahon's hearty unctuousness, Richter adds a layer of deadly irony to O'Brien's show that slows down the hour.
O'Brien's own natural pep, nervous giggle, and goofy variations on talk- show conventions (he commenced a recent show by bellowing, ''Are you ready to rock?!'') give his Late Night some fizziness. And any show that gives eccentric-waif singer Jonathan Richman his national television debut has its heart in the right place. There's a tad too much of the aren't-I-clever? college party boy in his manner, but O'Brien's overriding problem isn't his fault: He's a transitional figure, a 30-year-old working in a middle-aged genre. That means he can't work in too many obscure guests or youth-cult references without losing chunks o' ratings as older viewers flip the channel, muttering, ''What the devil is that kid talking about?''
O'Brien's lead-in, The Tonight Show with Jay Leno (NBC, weeknights,11:35 p.m.-12:35 a.m.), is conducting business as usual: ''Who'd believe we'd see the day when Yasir Arafat gets better press than Michael Jackson?'' ''In Washington, D.C., they spent $400,000 to redecorate the Oval Office. Four hundred thousand? Kind of makes you miss the thriftiness of Nancy Reagan, doesn't it?'' Oh, no it doesn't, Jay, and you know it.