THERE WAS a time when garlic was to Americans almost as conslusive a class giveaway as a Cockney accent to the English. Like a dropped h, a blast of garlic breath was enough to relegate anybody to the category of proles and peasants.

Charity and the democratic spirit assumed that such people could rise to the level of blandness that went by the name of refinement in the United States. But so long as that rich, unmistakable odor hovered around them, they hadn't made it.

World War II took the word "dainty" out of most people's vocabularies. It also put garlic into chic dining rooms. The wooden salad bowl, rubbed with a cut clove of garlic, became as reliable a mark of with-it modernity as pale birch furniture.

Beyond the salad bowl, though, garlic was still considered a bit racy. One magazine writer had this advice for those wishing to be admired for their casseroles: Put garlic in everything but never admit it's there.

It was a little like rouge. Not too much, dear.

Even after garlic became a fully respectable ingredient for the cook, it had etiquette problems. People were forever recollecting in the midst of a lunchtime Caesar salad that there was a job interview scheduled for the afternoon. Frantic recourse to peppermint Lifesavers. Furtive investments in mouthwash.

Smell remains the last prudery for a lot of people. The person who has dined on that wonderful beef roasted under a garlic crust may feel embarrassment seeping from every pore the next day. In fact, such a person may feel quite a bit like Kafka's Gregor when he woke up with too many legs.

Whatever e'clat there may be in sending home postcards from the exuberant French garlic festival held annually at Arleux, there's still a tendency for Americans to keep garlic at arm's length. We in this country eat a genteel pound of garlic a year per capita while Thais and South Koreans are eating 20 pounds.

Pervasiveness is the thing. It's true that if you rub cut garlic cloves on the soles of your feet, your breath will acknowledge it. And if you let yourself go with the American Cafe's broccoli salad, everybody will know.

On the other hand, would anything less potent neutralize the evil eye, cure diseases and keep vampires at bay? The Roman gladiators who ate garlic before going into combat must have known something. Scientists are beginning to think the mothers who hung garlic cloves around children's necks to prevent colds knew something.

None of which helps at all when two who, but a moment ago, were gaze to gaze, their "eyebeams twisted on a double string," look down at the menu. Ah! Pesto! Aioli! It's been the moment of truth for more than one relationship trembling on the edge of liaison.

Some try to sidestep the test by an I-will-if-you-will approach. Majorcan chicken cancels out Brandade de Morue. Your fumes and my fumes, becoming our fumes, can't offend either of us.

Except that they do. At that, it's probably just as well to get your priorities straight early in the game.