The crazy, mixed-up quality of the Reagan administration's approach to Central America came nicely into focus while the CIA's No. 2 man, Adm. Bobby Inman, was angrily putting on his slide show of aerial photos in the State Department auditorium to prove that Nicaragua is fast becoming a Cuban-style "Soviet bastion." That same day, the State Department's spokesman, Dean Fischer, was earnestly brooding out loud in the press room about the possibility of "irregularities" in Guatemala's election returns.

Inman was "angry," not so much at the Nicaraguans, as he was at the need (in the land of the free) to justify whatever the administration has in mind for the region--military intervention, "going to the source"?--with reasonably persuasive evidence. Still, his evidence was arguable.

Fischer's stern demand for prompt assurance that the Guatemalan vote be "fully and accurately counted," on the other hand, was merely laughable.

But not in Guatemala. A Guatemalan listening to the hand-picked candidate of the bloody-minded military government, Gen. Angel Anibal Guevara, as he claimed to have "won these elections freely and cleanly through hard work," could die laughing.

"I am going to defend my triumph in the streets, if necessary," the general said, and you better believe him. He is a former minister of defense. The defense ministry, according to Amnesty International, helps draw up the "death lists" that have given the Guatemalan government its well- earned reputation as perhaps the hemisphere's most murderous. In a quarter-century of military rule, Guatemalan "security forces" have slaughtered tens of thousands of opponents, suspected dissidents and innocents.

The government has weathered two leftist insurrections. It is now wracked by a third, and Assistant Secretary of State Tom Enders, in charge of hemisphere affairs, has rated Guatemala as "ultimately the chief target for Cuba and the Soviet Union" in Central America. But its criminal human rights record has disqualified it for American support even by the Reagan administration's permissive standards--beyond several million dollars worth of jeeps and trucks.

So what was being laid on us at the State Department last week was a pretty grisly catalogue of analogues.

First, Nicaragua shaping up as "another Cuba"--only worse. "This time the ocean barriers aren't there," said Inman. "They can move more easily into Central American countries."

Second, a supposedly irrefutable Soviet-Cuban-Nicaraguan connection with the insurgency in El Salvador, which could turn that country into yet "another Cuba"--only worse. It, too, is on the mainland, abutting not only Honduras but Guatemala. Meantime, to congressional critics and a lot of other people, El Salvador already looks all too spookily like "another Vietnam."

And finally, in Guatemala, "another El Salvador"--only worse on two counts. First, it is the biggest country in Central America (the size of Ohio), the most populous, with heavy U.S. investment; it has oil, it borders on Mexico, which has a whole lot of oil and borders on us. Second, the new government offers scant promise of the change of heart on human rights that would qualify it for American backing, Salvadoran style.

Even if the administration found some pretext, Congress, which is already sour enough on aid to El Salvador, would almost certainly resist. So where are we, analogue-wise: "Another Cuba" or two, "another El Salvador," another Viet . . . "?

Eureka! Which is to say that we may just have stumbled on one Vietnam-era analogy in all this that even the administration cannot reject: the compulsion of our crisis managers, then as now, to deal in the shorthand of ill-fitting and often unfulfilled analogies.

We went into Vietnam, remember, to avoid "another Munich." If we didn't "draw the line," Dwight D. Eisenhower's "dominoes" would fall. As variously identified, they came to include not just the rest of Indochina (Laos and Cambodia) that did fall, but a long row that didn't: Thailand, Burma, the Philippines, Indonesia, Australia. (Lyndon B. Johnson threw in Honolulu.)

The "domino theory," in short, is not a reliable analogy. In the grim way the administration is now applying it to Central America, it invites another clutch of analogues, closer to hand but no more reliable: "Another Cuban missile crisis"? "Another Bay of Pigs"?

A sounder approach might be one for which no analogy comes to mind. You could begin by asking why, if neighboring Mexico is the ultimate "domino," it has taken so dime a view of the administration's policy? If Ronald Reagan is serious about ruling out "brute force," as he has said he is, his best hope almost certainly lies in less theater in the State Department auditorium and more strenuous and accommodating diplomatic efforts--in concert with the Mexicans.