THE ALBUM -- Steely Dan, "Gaucho" (MCA 6102).

Some pleasures in life come disguised, like geodes. Steely Dan's "Gaucho" album wants several playings before it opens up to the listener its jagged little gems of backspin English and left-footed jazz.

"Gaucho" sounds almost smooth from a distance, trademarked by Donald Fagen's thin, intense vocals and the syncopated leaning toward brass and synthesizer. Trademarked almost to sterotype, in fact: You can identify the artists from 40 feet.

But Fagen and cohort Walter Walter Becker display their characters through a viewfinder, and slowly the depth of vision increases. The casual wrinkles turn out to be rather intriguing scars. The songs themselves begin to emerge from the screen of Steely Dan sound, and the black-and-white snapshots develop a whole range of grays and sepias.

Nobody said music had to be easy. If most composers prefer to define their narrators, okay, but Becker-Fagen create characters by implication. No explanation is provided, nor any absolute setting: The listener has to get into the song, walk around as the narrator and then figure out where and what he is.

The ambiguities exist partly to protect the characters' uniquely seamy intimacies; through this album dodge assorted sexual proclivities, various illegal drugs and secret violence. "It's hard to dispense certain information," concedes Fagen, although with "Gaucho," he believes, "we're giving better signals, choosing better clues."

Well, perhaps, but the very elusiveness of the Steely Dan people make them fascinating. The way to tell whether you're deep-dreaming or half-awake is by your point of view: If you see yourself as a whole body, you're at least partly awake. If you are seeing from behind your face, as in real life, you're asleep. And to comprehend the voices in these songs, you have to wear the mask.

That may require a leap of faith, in some instances. The "I" of "Babylon Sisters," the opening track and one of the album's finest moments, has abandoned himself to the arms of a pair of young temptresses of his own creation. The narrator of "Glamour Profession" holds the "L.A. concession" on cocaine: Local Boys will spend a quarter Just to shine the silver bowl Living hard will take its toll. And the narrator of "My Rival" has a rather endearing allegiance to the Phillip Marlowe school of social relations: I struck a match against the door Of Anthony's Bar and Grill I was the whining stranger A fool in love With time to kill.

These characters have in common not only the purest self-interest but also a kind of alienation. They are lonely or hurt or wistful or skeptical: The dope dealer recalls, "I drove the Chrysler/Watched from the darkness while they danced." The aging BMOC who desires the sweet young thing in "Hey Nineteen" admits ironically that "We got nothing in common/No, we can't talk at all." And the pompous and embarrassed lover tries to hurry his young protege away: Just when I say "Boy we can't miss You are golden" Then you do this. . . Can't you see they're laughing at me Get rid of him I don't care what you do at home Would you care to explain

As always, the guest musicians are of the highest quality, including the Brecker brothers, Mark Knopfler, David Sanborn, Tom Scott, Rick Marotta, Rick Derringer and Michael McDonald.