It's been a poor season for spies. They just aren't what they used to be.

The latest in a long line of examples is Ronald W. Pelton. Given what's being disclosed at his espionage trial in Baltimore, no wonder the government doesn't want the press to speculate about that spy case. The more we learn about it, the more embarrassing it becomes.

Of the Pelton case so far, it can be said that it provides the best argument yet for an Official Secrets Act, and not because it demonstrates the need for such an act to keep supersensitive information from falling into the hands of America's enemies. In this case, the Soviets already have the information, according to testimony. But imposition of an Official Secrets Act would save the government from having to respond to embarrassing questions about many aspects of that case, such as:

How is it possible that a National Security Agency employe with access to extraordinarily sensitive top-secret information could walk into the Soviet Embassy two blocks from the White House, in mid-afternoon of a busy weekday in Washington, without being detected?

It isn't as if Pelton performed some brilliant cloak-and-dagger act to gain admittance to the embassy, say in a laundry cart or bread truck or other conveyance favored in fictional lore to shield a spy from sight. He simply picked up the phone on a Wednesday afternoon, dialed direct and identified himself as being someone from the U.S. government.

Then he told the person on the other end of the line that he had "something . . . that I think would be very interesting to you." He didn't try to disguise his voice, either, by employing one of those tricks-of-the-trade voice adapter devices that makes a good spy sound like someone else, or maybe like Donald Duck.

His conversation is, of course, tape-recorded by our guys listening through electronic surveillance. A full 22 hours elapses before Pelton calls again. Presumably, an alert has sounded, or should have.

When the second Pelton call comes through, logged by our side at 2:32 p.m. on a Thursday, he goes through his disclosure drill again: "I have . . . some information to discuss." Then he fumbles around asking self-incriminating questions about how best to enter the embassy. "Will it be safe for me to come at this time?" he asks. And just how should he enter? he wants to know.

Certainly it's safe, he's told. Come right in the front gate in full view of all on 16th Street. Okay, Pelton, says, he'll be there in two minutes, thus letting the American eavesdroppers know exactly when and where to look.

By now, alarm bells are ringing all over top-secret Washington. Surveillance teams are posted discreetly around the embassy. Hidden cameras are ready to record the arrival of this most intriguing government employe who wants secretly to tell the Soviets something they'll find most interesting. Right? Not at all. Nothing happens. Pelton goes directly in, without disguise or even a Howard Hunt red wig, and directly out. No one picks him up or follows him. If his photograph is taken, they don't, as the cops say, "make him."

Had they done so, even greater alarm bells might have sounded. Pelton turns out to have left the supersecret NSA recently as a bankrupt, a condition that instantly triggers, or should have, an immediate security investigation of his activities. Apparently it doesn't. Why not?

More questions: What does his case, and other recent such bumbling ones that have come to light, say about personnel practices of our vital intelligence agencies?

And speaking of bumbling, the way Pelton finally is caught raises another embarrassing subject. Diligent American intelligence work doesn't get him. In the end, it's a Soviet defector, the infamous Vitaly Yurchenko, who fingers Pelton.

Yurchenko is the apparent Soviet intelligence agent who later redefects to the Soviet side by simply getting up from a table in a Georgetown restaurant where he's dining with his American "keeper" intelligence agent, then strolling up Wisconsin Avenue and into a Soviet Embassy compound.

They should have clamped an Official Secrets Act on that one, too. That way everyone, Americans and Soviets alike, would have been spared further embarrassing disclosures about the sorry state of espionage in the mid-1980s.

All of this would be farcical, if it weren't so deadly serious.