Is grossness on the way out in TV humor? ''There's a swing back to clean comedy,'' says Thom Sharp, co-host of The 1/2 Hour Comedy Hour (ABC, premiering tonight, 8-8:30 p.m.m).
This new show, which the producers call ''zany,'' promises to concentrate on broad sketches and sight gags in an attempt to win back to comedy the general audiences that have abandoned it because of the drug, sex, and scatological nature of so much of the material.
Many TV viewers have been ''turned off'' by the grossness of the material on such shows as ''Saturday Night Live'' (NBC), ''Not Necessarily the News'' (HBO), and the Richard Pryor and George Carlin specials (HBO).
Tonight's premiere, which was not ready for screening at press time, features special appearances by Burt Reynolds, Joan Collins, and Henny Youngman, as well as topical comedy by hosts Thom Sharp and Arsenio Hall.
''It's much harder to do clean comedy,'' Thom told me. ''Some comedians get up and say dirty things and the audiences applaud like mad. Then, if I get up and tell a joke about nuclear reactors, they sit on their hands for a while. The clean, observational humor that Bill Cosby and David Brenner do is the most difficult kind of stuff to do. It's much easier to stand up and say X-rated words and get a big laugh from the kids.''
Mr. Sharp says his new show is using some of television's top writers - people who usually work for Joan Rivers, Richard Pryor, ''Saturday Night Live,'' etc. ''But we have to make sure they don't go for the jugular,'' he says. ''We need 8 o'clock material.'' He indicates that one of the main advantages of doing a summer show like ''1/2 Hour'' is that you can get such top writers while they are on hiatus.
''But I hope parents will realize that our 8 o'clock show is the kind of program the whole family can sit down to and relax with. After all, a family that laughs together . . . is . . . not likely to be beating up on each other.''