It's news when the arts are rejected, censored or prosecuted as presumably morally offensive. But how can or should news stories show or describe the works without themselves being offensive? Their own audiences are usually wider or at least less self-selected than the artists'.

That question has come up repeatedly lately, most recently in stories about MTV's refusal to air on cable TV the big video by the uninhibited rock superstar Madonna, "Justify My Love."Newspeople also had to reckon with how far to go in trying to make clear why there were furors over Robert Mapplethorpe's photos, the 2 Live Crew lyrics from the "As Nasty As They Wanna Be" album, "raunch radio" or Bret Easton Ellis' novel "American Psycho," to name some of the most prominent cases.

Some news media have tested their own standards of acceptability by quoting from or showing the material outright. At least one TV news station I know of apparently exploited the Madonna video for ratings. Most have tried to describe circumspectly but with reasonable candor.

- THE MAPPLETHORPE exhibit included sexually explicit photographs, including seven declared obscene by a grand jury in Cincinnati, and led to the trial and acquittal of the director of the Contemporary Arts Center where they were shown.

When the photos were hung in Boston's Institute of Contemporary Art, the public TV station WGBH aired the same seven. It received 120 phone calls, which it said were mostly favorable, though the station is facing an FCC investigation. One other station showed what it deemed the less objectionable photos and described the others. At least one censored the photos with black patches.

I know of no newspaper that used anything but cropped versions of the photos, although many described them rather fully.

- THE LIVE 2 CREW rap group was found not guilty of obscenity in a Fort Lauderdale, Fla., trial. A merchant who sold the album was convicted.

In Fort Myers, the News-Press opted not to print the lyrics. But the executive editor was incensed by the prosecution, arguing in a page one editorial that the people, not the government, should decide what is obscene. He offered a copy of the lyrics to anyone over 18 who came to the newspaper's office "so they can assess both the decision of authorities to ban the album and our decision not to print them."

George Will, in a Newsweek column, quoted generously from the lyrics to convey his sense of outrage over their blatant vulgarity, sexual rage and hatred of women, but I've seen them nowhere else in print.

In this case, at least, print seems to be more shocking than the performance. That was a point also made when the 2 Live Crew case was discussed by a panel on the John McLaughlin cable TV show last month that debated whether album warning labels should be made mandatory. McLaughlin suggested that the rap group may have been exonerated because the jury couldn't make out all the words of the performance, whereas the words were clear enough printed on the album.

McLaughlin said he couldn't use the actual words on the air but paraphrased them adequately.

- THE BEST DESCRIPTION of the Madonna video I've seen was in the New York Times, which said it "depicts the star's kinky sexual fantasies while making love with her real-life lover, Tony Ward, in a Paris hotel room. In a series of jump-cuts, the video moves back and forth between shots of the partly undressed couple kissing and caressing and the woman's fantasies, which range from thoughts of being observed to images suggesting dominance and submission, leather fetishism and bisexuality."

While the Times said the video was neither hard-core pornography nor as sexually explicit as Madonna's recent "Blond Ambition" tour, which HBO broadcast live from Paris, it was clearly raunchier than mainstream over-the-air entertainment.

MTV broadcast only a heavily edited version of the video and then only to explain its decision not the carry it on its regular programming.

The pay-TV channel Video Jukebox, however, has decided to use it.

And ABC broadcast it in its entirety on "Nightline" (Ch. 4). Host Forrest Sawyer led into the show with a disclaimer, "Obviously we are broadcasting late at night [11:30 p.m. in our time zoneT and we don't expect children will be watching," and "you should know this video contains graphic portrayals of sexuality and nudity." Interviewed on the show, Madonna admitted her video "bent the rules" but argued "that's what art is all about, experimenting."

The news show that appears to have crassly exploited the Madonna story for ratings is the Fox network news on New York Channel 5. It teased with excerpts in its early evening news show of Nov. 29, in the sweeps period. It showed the full video at the end of the broadcast but fuzzed out some of the most explicit scenes as the steamiest simulated sex and shots of a woman wearing nothing but suspenders above the waist. The station also had a telephone poll on whether the video should be banned from TV (54 percent of the callers said yes, but most likely viewers most outraged by the video were more inclined to respond.)

- WHILE THEY DIFFER on their approaches to showing the material that is under assault, virtually all news media come down foursquare for the rights of the artist when the issue is government intervention in the arts.

That is true even when the critics have found the works disgusting or with little redeeming value. Deploring "marketing cynicism and vulgarity, " John Leo of U.S. News & World Report wrote that "short of censorship, everything possible ought to be done, beginning with a serious national debate. Maybe it will come down to boycotts. Maybe we should recycle Nancy Reagan's slogan, `Just say no.' "