ASIDE FROM the usual assortment of automobiles, gold chains, would-be screen writers and exposed flesh, the one other thing Los Angeles in not short of is platoons of tourists eager to experience some of the above. The appropriate city bureau estimates that a fearsome 12.1 million people came to call in 1981, and by some counts this is the most visited area in the entire country.

Los Angeles does not keep tabs on how many of those who arrive leave a bit baffled and disappointed, but that number may be considerable as well. For despite its vaunted air of "have a nice day" friendliness, L.A. probably is the most difficult city in America for casual visitors to understand. One can arrive in New York, go to the museums, the theater, the shops and restaurants, feel the excitement on the streets and understand the place's continual lure.

Los Angeles is different, and more than one irate easterner, after huffing and puffing about what an empty, vapid place this is, finally will wind down and admit with a shrug, "I just don't get it." And no wonder. For the truth about Los Angeles is that it is a secret city, one that reveals its deeper charms so grudgingly it is almost impossible for a first-time visitor to discover them.

Consider, for instance, how the cards are stacked against the outlander. Los Angeles is preposterously spread out over 70 square miles linked by a disconcerting web of ever-busy freeways. You must have a car to get around, but once in that car you may not be able to decide where to go. For this is a city that scorns the idea of a center, that is proudly Balkanized into dozens of self-sufficient communities, each with its own name, specific characteristics and partisans. The most telling question you can ask an L.A. resident is not what he or she does for a living--answers there tend toward creative obfuscation--but where they live. Placing people in Silver Lake, Echo Park, Mar Vista, Brentwood, Venice, Santa Monica, Marina del Rey, Bel Air, Pacific Palisades, Encino, Studio City, Century City, Culver City, Hollywood, West Hollywood, North Hollywood, et al., says as much about them in terms of sociopolitical orientation and cultural bias as one is likely to discover in casual conversation.

Another problem with L.A. for visitors is that the major concentrations of hotels are in totally unrepresentative areas that locals tend to avoid. Though downtown L.A. is nominally where the city started, it is treated as just another neighborhood, and not a hugely desirable one at that. Beverly Hills, despite or perhaps because of the capitalist excesses of Rodeo Drive, irritates as many people as it entrances, and is about as typical of L.A. as a whole as the enclaves of Foxhall Road are of Washington.

Even more off-putting for the intelligent tourist is that L.A.'s attractions seem to be aimed at the unsophisticated. How much pleasure, after all, can a sentient adult take in Disneyland, the Universal Tour, Knott's Berry Farm and the cement footprints of Mann's Chinese Theater? Yet the trick of coming to love Los Angeles is not to get mired in the obvious, but to go beyond it. Every cliche you've ever heard about this city is true, but what makes L.A. a fascinating place is how much more there is to it than those bromides would ever have you believe. And because those facets tend to be hidden among the dross, they take on additional charm, like discovering the Whore of Babylon collects pre-Raphaelite drawings on the side.

Among the attributes of L.A. that intrigue residents are:

* Its ethnicity. Los Angeles is not just the home of bored movie types with swimming pools, it is an intensely polyglot city, with a thriving Chinatown and Little Tokyo within blocks of each other, enormous Korean and Mexican communities, Thai and Vietnamese enclaves, and more.

* Its architecture. Yes, the hot dog stand shaped like a hot dog is charming, but L.A. also is home to some of Frank Lloyd Wright's most innovative buildings, the intricate bungalows of Greene and Greene, the clean, lyrical International Style houses of Rudolph Schindler and Richard Neutra, and the downtown Bradbury Building, with probably the most beautiful inner courtyard of any structure in America.

* Its bookishness. Not only does the city boast a cross section of used, special-interest and antiquarian bookstores that puts many eastern metropolises to shame, it also contains the Huntington Library, one of the great repositories of first editions and manuscripts in the entire Western world.

* Its closeness to nature. Sometimes visible in the worst possible ways--fires, floods, earthquakes and power outages--the physical world makes a considerable impression. Areas for hiking, camping and skiing are extremely close, as are the famous beaches and scenic vistas, and on good days--which far outnumber the smoggy bad--the air can be as sweet and caressing as a heady champagne.

That is a limited selection of the city's virtues, and a distinctly personal one to boot, but that is part of the point. No matter what your interests, if you give this city time and an open mind, if you do not come out here, as many easterners tend to do, determined to put the upstart in its place, you will discover more than enough to appeal to almost any taste.

And if you come to live here, Los Angeles' prime attraction, its blessedly casual style, gradually will make itself visible and attractive. You will come not merely to tolerate but to love the freeway system, both for its efficiency and for its sheer physical grandeur. You will get used to looking into your rearview mirror and seeing clowns in full makeup on motorbikes, to listening to teen-age surfers grumble knowingly about what the kelp beds are doing to the waves, to hearing the latest tales of noveau riche monetary excesses (like his and hers stained glass windows) that sound more innocent than corrupt.

You will come to cherish a mode of life that is more human, less grating and ultimately simply more livable than wherever it was you left behind. And most of all you'll accept without questions the idea that yes, no matter what it looks like or how it's laid out or how others may tease it, Los Angeles is a true city and a great one.