Near the end of tonight's "Barbara Walters Special" on ABC, Barbara Walters says from behind her invisible pulpit, "We, the public, are very hard on our idols." We certainly are, Babsy. We subject them to being interviewed by you.

No -- just kidding. Who would want to bother to try to get along without Barbara Walters? Barbara Walters -- manicurist, pedicurist, guru of Kitsch, yenta, maven, gadfly, blabbermouth and Mother of Confessor to the world. Tonight Barbara talks with Bo Derek, Farraw Fawcet, Cheryl Ladd and Bette Midler and each segment is, in its own insane way, insane -- and, also, quite wonderful.

It's a theme show -- at 10 on Channel 7 -- and the theme is, four blonds, orthodox or reformed to "crossroads" in their lives. of course, by the Walters definition, anyone could be deemed to be at crossroads at any moment, like maybe a crossroads between a lull and a lapse. But glib chatter calls for slender threads.

The Derek piece, first, is the most unintentionally revealing of the group, since Derek's so-called "svengali," the highly protective John Derek (once an actor) joins Bo and Barbie on a great sea of pillows, with Walters in her gypsy fortune teller outfit and Derek Homme doing much of the talking.

"Bo is my everything," he says. "I hate work," he says. "I'm not her Svengali," he says. "I haven't used or abused her," he says. He rubs her leg. He dabs a drop of sweat off her nose. And from Bo there is barely a peep.

Then it's off to Farrah's house.

Farrah has a "concealed media wall." Walters points out. It sounds like somthing Mike Wallace would hide behind with a film crew.

Walters is more than fair to all her guests. She doesn't ask Ladd about her broken-down marriage to Alan Ladd's son David, and she calls Ladd's so-so TV special "An enormous hit." In the same vein, she neglects to mention that Farrah Fawcett's movies have been such disastrous bombs that she's had to come crawling back to television to remain the pupil of the public eye.

"I'm lonely," Farrah says. "I want to have a baby." It is suggested she might want to visit a sperm bank. Really. But it turns out Farrah is having an intense spiritual relationship with the deeply cute Ryan O'Neal.

"This part of my life is so special to me," says Farrah into Barbara's bursting-with-understanding eyes. "I have so much growth now that it's like I'm bursting." Farrah looks beautiful, but no one on the show can quite compete, visually, with the opening shot of Bo Derek jogging on the beach in a thin, filmy white smock. So thin. So filmy. So smockkkkkkkk. . . .

Why, you can see right through it, practically!

Walters asks her guests to rate themselves on the banal 1-to-10 scale. Farrah says "a nine, barely a nine." Cheryl Ladd says, "A good solid eight," but on Fridays, a seven. And Bette Midler, last and lustiest, replies, "Oh, I think I'm about a 55. I don't know. I'm a happening girl."

Midler is probably the toughest nut for Walters to crack since she played ring around the rosie with Richard Pryor. "Get out of my house," says Midler at one point, but the adorable brassy, sassy actress and singer is only kidding. Too bad. It would have made a great television first.

Midler recalls a tormented teenhood ("I had this set of knockers"), recalls baring her bazooms at the London Palladium, concedes both "I'm sexy" and, "I'm an oddball, I'm definitely odd"; and gives her house the white glove test: "That windowsill is perfectly filthy."

Sometimes fluff has a way of seeming substantial, marginalia works itself in past the margins, things you needn't know become fascinating, and mindless escapism gets to be totally engrossing. the time has come to admit that it would be unthinkably painful to have to part with Barbara Walters and to propose that every one of her interview specials be earmarked straightaway for the time capsule -- dipso facto, lickety-split post haste and quick, like a bunny.

We, the public, are very hard on our Barbara Walters. But she's the only Barbara Walters we have.