NBC's "Buffalo Bill" boasts the most luminous cast seen in a situation comedy since "Cheers" premiered. Dabney Coleman is at his oily-eely best in the title role; Joanna Cassidy deftly deflates him as a caustic and comely coworker; John Fiedler, once the most nearly hopeless patient on the old "Bob Newhart Show," plays another colleague, and Max Wright, a tirelessly versatile and inventive character actor, plays the manager of the TV station where Buffalo Bill works.

And all these talented people are tied up in what turns out to be, at 9:30 tonight on Channel 4, a pretty nasty business. "Buffalo" Bill Bittinger, a contentious talk show host at a Buffalo, N.Y., TV station, is a bounder, a cad and a louse--"unbelievably selfish," as one character describes him, and flagrantly unredeemable. There is no such thing as the pleasure of his company.

Tom Patchett and Jay Tarses, the MTM alumni who created the show and wrote the premiere (which Tarses directed), are veteran comedy writers who have tried their best to work around the fact that their central character is a rotter, a Pal Billy so callous that his first reaction to the death of a close friend is to make a shameless grandstand play for the fellow's job.

Archie Bunker was no hero, but he was able to capture the heart as well as the attention of a nation because there was poignance in his perpetual battle with a changing world, and because stingingly valid points about human nature and social inequity could be made through him. Buffalo Bill exists primarily as a comment on the sort of grandma-stomping ruthlessness found all too frequently in show business. Another show about show business is just what television needs not.

In innumerable movie roles, as well as his career-launching turn on "Mary Hartman, Mary Hartman," Coleman has made an art of playing the conniving boor, the way Franklin Pangborn once held the patent on sissified fops and Arthur Treacher owned the British butler. The portrayal is given an added wrinkle by the fact that Bittinger is an incurable small-timer; it's gruesomely obvious that he'll never be more than a big fish in a small and often frozen pond.

Coleman is fun to watch, even creepily fascinating, but that isn't enough to give the character much stature, and watching Bittinger's associates suffering his follies week after week does not present itself as a durable sort of treat (the series is getting a test run this summer for a possible spot as a mid-season replacement next fall). Canned laughter that roars at Buffalo Bill's swinishness only makes the show that much more harsh.

However, it is gratifying to have Max Wright on any screen in any role, because he is one of the cleverest actors about. He has more up his sleeve than Mr. T. Wright was a mainstay for years at Arena Stage here. He gives the put-upon character he plays a winning, daffy dignity. Cassidy is amusingly jaundiced about life with Bill, who is totally transparent, but whom she sees through, 20/20, all the time. He's so oblivious, he doesn't have the sense to be insulted when she refers to a brief affair the two once had as a "mutant romantic interlude."

"Buffalo Bill" bears a resemblance to another series NBC aired during the doldrum months--"Good Time Harry," six episodes of which were produced and shown from July through September 1980. Harry was a lout, too, a toweringly insensitive sports writer on a big-city newspaper, but he had more dimension, and his comeuppances had more point and bite than Buffalo Bill's do. "Harry" was created by Steve Gordon, who later wrote and directed "Arthur" and who died, last November, at the age of 44.

NBC should dust off those "Good Time Harry's" and replay them--not as a memorial, but because they were brilliantly funny--when "Buffalo Bill's" defunct.