WHEN Washingtonians go to the grocery they buy quail eggs and collard greens, large curd cottage cheese almost three times as often as small curd, 19 percent more yogurt than the national average, 14 percent more butter than the national average, and lots of frozen pies.

It's possible at some stores in the Washington area to come face to face with 250 to 300 varieties of cheese from all over the world, dozens of kinds of salami and 10 or 12 kinds of caviar. And it's not uncommon in neighborhoods like Adams-Morgan and Capitol Hill, where rich and poor live side by side, to see Perrier water sharing the shelves with canned hash.

So what do Washingtonians eat? Vincent Dole of Dolefam Corp., a food importer, says, "What distinguishes Washington is the international scope of foods being demanded and offered" here. "Washington attracts people who do a lot of traveling," Dole says. And those people, through their travel, Dole says, "develop an appreciation for good quality." What Dole and others assert about the peripatetic qualities of Washingtonians is borne out by the statistics: Washingtonians lead the nation in foreign business trips and American Express Gold cards per capita, according to Mediamark Research.

And many Washingtonians are lucky enough to be able to indulge the tastes they bring back from Paris or Zimbabwe. The Washington metropolitan area enjoys relative affluence and has relatively little poverty compared with other American cities.

"Washington is the last place in the world a manufacturer would test his product," says Karen Brown of the Food Marketing Institute, "because it's not considered typical."

What makes Washington atypical is its transience (thanks to national elections), its large foreign contingent, the fact that the number of single people in Washington is twice the national average, and the lack of a sizable population of blue-collar industrial workers--those families that in most American cities keep the wheels of food commerce going round. As a result, the "incidence" of purchase of the mass-marketed, mass-advertised and mass-produced foods like cake mixes and powdered soft drinks tends to fall below the national average, according to Claritas Corp., a firm that specializes in telling the world of commerce and politics what the population of any ZIP code in the country could be expected to read, buy, use, do or eat.

Claritas' PRIZM data system can give us specifics. More than 44 percent of Washingtonians fall into the highest two income groups that Claritas classifies, compared with a little over 13 percent nationwide. And not quite 8 percent of Washingtonians fall into the poorest urban group that Claritas classifies, compared with 23 percent of New Yorkers and 21 percent of Baltimoreans.

Yogurt is often associated with highly educated and fairly wealthy populations, a group that Claritas refers to as "money and brains." Yogurt rates 119 on PRIZM's selection scale, meaning that we Washingtonians reach for yogurt on the grocer's shelf 19 percent more often than the average American.

Washington's next highest selection index is for butter, at 114. People in the city like it even better (127) than people in the suburbs (110). The selection index for rye bread is 108, versus white bread, which stands at 94 for the metropolitan area.

Washingtonians also use frozen dessert pies and cakes more than the average American (a selection index of 109), which probably says more about the need to get dessert on the table quickly than it does about sophistication. And Washingtonians use flavored and seasoned rice mixes 11 percent more, probably for the same reasons.

According to PRIZM, in the poorest neighborhoods of Washington, food shoppers rely on canned meat of all kinds, especially canned hash. The poor use starchy things like boxed and canned pasta more than the national average. Poor people prefer white bread more than the affluent do, and they use canned fruit juices more than the average.

And what are the affluent buying? Ann Brody of Giant Foods' new Someplace Special in McLean has some figures on that. In one week, the store sold 10 pounds of smoked salmon cream sauce for pasta (without the pasta), 76 pounds of Italian Bel Paese cheese, 67 1/4 pounds of country pa te' and 48 1/2 pounds of pa te' maison, 1,100 pounds of fresh pasta and 117 pounds of chicken salad.

And brie. "Do we sell the brie," sighs Brody. In one week the store moved 22 pounds of raw milk brie, a stronger product that generally demands an acquired taste, and 86 1/2 pounds of 60 percent butterfat brie, the highest butterfat content of any brie. These figures don't count the lower butterfat bries, or those flavored with herbs.

Murray Goldstein of Dairy King Inc. can put the brie figures in another light. "In Baltimore I'd sell 10 to 12 times as much longhorn cheese as you would in Washington. But in Washington I'd sell maybe 20 times the brie. This is a beer-drinking town," Goldstein says of Baltimore. "Washington is wine."

Robert Eacho, a cheese importer who has written a book for prospective cheese entrepreneurs, puts consumption of brie at about 50 percent of total local consumption of French cheeses. But Eacho offers one qualification to our unbridled affections. Like most Americans, Washingtonians want their brie neat and orderly. They want a fluffy white rind with no brown spots. But they also want their brie to be fairly ripe. And, says Eacho charitably, "it's difficult to have both these things at the same time." So although Washingtonians love their brie, according to Eacho, they are willing to go only so far with it. They want it to be terrific, but not that terrific.

The question naturally arises: Just exactly where do all these affluent Washingtonians stand on the sophistication scale? It's difficult to quantify, but as one produce wholesaler pointed out, "Five years ago you didn't see French green beans the tiny ones anywhere. Now they're in the Giant, at Neam's, at Sutton Place Gourmet." A specialty food importer, Eli Schlossberg of Castle Foods, says, "The sophistication is there, but Washington has a way to go. Everybody wants to open a Zabar's," Schlossberg says, referring to the gigantic New York food emporium, "but you need unbelievable volume."

Ann Brody calls Washington a city in transition. "A fascinating evolution is taking place," Brody says. For example, "I put 85 pieces of a saute'ed Korean wonton in my case last week and sold it all in an hour. That wouldn't have happened five years ago."

Washingtonians' mobility has more to do with this awakening than economic or ethnic makeup, Brody thinks. At first, she says, "People look for food that's familiar, comfortable. They want what they grew up with. But as people are exposed to different things they begin to buy different things."

As a testament to Washingtonians' mobility, try asking any 10 Washingtonians if they know what to do with quail eggs. Quail eggs are not exactly a staple of the American diet, yet a shop like Sutton Place Gourmet sells 1,000 of the tiny things every month. Told that 1,000 quail eggs sounds like a lot, Sutton Place owner Jeffrey Cohen is incredulous. "That sounds like a lot?" he says. "Do you know how many quail eggs it takes to make an omelet?"

Cohen also talks about Washingtonians wanting value for their money. "If the price is right, they'll buy it from you," Cohen says. In some cities, the price doesn't even have to be right. Vincent Dole of Dolefam says, "In New York consumers are more aggressive about new foods because they are a fashion item there. People in New York rush all around town if . . . some little store down on 9th Avenue has a new kind of leaves from Turkey."

And in Cleveland or Pittsburgh shoppers will buy "an occasional this or that but there's not that deep or strong an interest" as in Washington, Dole says. Boston, he says "is really impressive. The range of items is not that great but the quality is."

Quail eggs and strange Turkish leaves notwithstanding, Dole and others report that the East Coast tends to lag behind the West Coast in food trends. While Washington markets still tend to separate "gourmet" items like virgin olive oil and hearts of palm into separate sections, for instance, on the West Coast "integration" or mixing of those things into the regular selection is the latest thing.