LOS ANGELES (AP) _ You know how you'll be standing in the grocery checkout line and you'll pick up one of those tabloids with the screaming headlines? And the story inside never lives up to the promise on the cover?

Fox has turned that kind of an idea into a television show, ''The Reporters,'' making its debut Saturday.

True, there are no stories, at least in the premiere, about aliens from outer space or two-headed babies.

But the first installment does tease with the promise to ''answer the nagging question - is Mike Tyson a homosexual?''

Never mind that no one who screened the show at the TV critics' convention here could recall ever hearing the ''nagging question,'' what seemed immediately more interesting than the answer was what happened to the person who asked.

Reporter Steve Dunleavy did put the question to Tyson, after a fashion, but the program never gives the promised answer, other than Tyson's mumble about such rumors being typical when you have all the money and women.

Otherwise, Dunleavy's piece is a rambling profile that reveals little that is new about the heavyweight champ.

''The Reporters'' begins with a dramatic, fast-paced opening similar to CBS' ''West 57th.'' What follows isn't really a news show, though the reporters from ''The Reporters'' defended it as such during a heated presentation to television critics.

Earlier in the week, the same critics got a peek at GTG's syndicated magazine show, ''USA Today: The Television Show.'' Questions about its ''Entertainment Tonight''-style of happy talk paled next to ''The Reporters,'' which makes ''USA Today: The Television Show'' look like ''CBS Reports'' by comparison.

On ''The Reporters,'' the reporters make less-than-subtle statements of their own conclusions about their stories. Getting the other side - or at least presenting it to viewers - seems an alien concept.

Dunleavy even suggested there was no difference between his editorializing in the Tyson piece and the commentary written by the TV critics who were questioning his tactics. He didn't seem to grasp the difference between clearly labeled opinion and something presented as objective reportage.

For instance, after Tyson tells Dunleavy he'd do something ''irrational'' to anyone wh threatened his wife, Dunleavy gushes in voiceover, ''And believe me, he means it 3/8''

Dunleavy is a veteran of Rupert Murdoch's tabloids in Australia and more recently worked at the Star and the New York Post. Murdoch owns Fox Broadcasting Co. Dunleavy is also seen on Fox's syndicated news show, ''A Current Affair.''

''The Reporters'' is from the same people who do ''A Current Affair,'' but that show somehow has an edge of wink-wink, nudge-nudge, thanks in part to host Maury Povich, that is lacking in the deadly serious and self-important ''The Reporters.''

Rafael Abramovitz, another of ''The Reporters'' who is also a veteran of ''A Current Affair'' became angry at the TV critics, at one point explaining his cracking voice - ''I'm trembling, because I'm offended 3/8''

Besides the Tyson piece, critics took exception to a story in which reporter Krista Bradford helped a Taiwanese student legalize her alien status and avoid deportation.

In the final scene, Bradford shows the girl a tape of an interview with a government official agreeing to let her stay in the United States. The girl, overwhelmed by the news, hugs Bradford. Then the crew takes her to the Statue of Liberty.

CBS' Dan Rather had some emotional encounters with traumatized Vietnam veterans for a recent network documentary and the network took the veterans to the Vietnam Veterans Memorial. But somehow it all served to illustrate the issue without becoming embarrassingly self-conscious.

Abramovitz disagreed. ''If you think they (the networks) work a story any differently than we do, they're a lot better at pulling the wool over your eyes than we are,'' he said.

''I think we can display emotion without commenting on the issues,'' said Bradford. ''I agree it's a fine line, and I'm happy with where I have placed it.''

Abramovitz called the show ''first-rate journalism.''

''We used to have a trick. We used to hide all these things and make it look like 'objective journalism,''' he said. ''I think it's time to come out in the open and tell it like it is.

'We're going to be doing stories about real people in a real way and we're not going to confuse people about what's on the screen or what's in our minds.''

The critics didn't get to screen Abramovitz's piece for the premiere show; the story, called ''The Actress and the Dwarf,'' was still being edited.

The reporters on ''The Reporters'' might have a point about elitism. Low- brow entertainment has its place, and who doesn't have a guilty pleasure?

Viewed as unintentional spoof of the ''60 Minutes'' genre, ''The Reporters'' is not bad entertainment. But calling it an objective news show is a little scary.

---

Elsewhere in television:

MORE ''REALITY'' FROM FOX - Fox has more ''reality-based'' series in production for the fall to fill in for entertainment shows delayed by the Writers Guild strike: ''Beyond Tomorrow'' is a science magazine show, the concept imported from Australia where it is a top-rated TV series; and ''Cops,'' in which cameras follow five Broward County, Fla., police officers for a week, then edit their stories together ''Hill Street Blues'' style. Fox says even if the strike ended tomorrow, it wouldn't be able to get ''Angels '88,'' its new remake of ''Charlie's Angels,'' on the air until January and would barely get its comedy ''Married ... With Children'' on in time for the November sweeps rating period.