IF YOU'RE hungry, I always used to argue, anything tastes good, and if you're not hungry, nothing does; therefore, the quality of food is irrelevant.

I am a Group A consumer - I expect nothing, require nothing, and the American food industry is built on me.

At home I am a tiger, however, and fodder there is of surprisingly high quality.

Naturally, if you eat at somebody's house, you can't very well say the rice is a slimy pitfall, nor can you bang the table if they slop chemical "chocolate" over the ice cream.

This natual politeness extends to restaurants, where I accept, like everybody else, the overdone asparagus, the underripe avocado, the hamburger that was okay last Tuesday.

I was in London last week where I ate as badly cooked a piece of lamb as ever saw a plate, even in England, in one of the most expensive places there.

Did I complain? How could I, being a foreigner? The English, like me, eat anything that's warm, hot or cold and no questions asked.

But I also had a cup of coffee at the Montcalm Hotel, and it was splendid. Of course it cost $1.20, but it was real coffee. It has opened my horizons, and I think I am about to become a member of Group B consumers.

They are the ones who expect food to be prefect.

My mother-in-law, of revered memory, was a Group B. She ate very little, but what she ate was flawless.

She lived in a small town in Virginia, which did not have very good markets. She has strawberries out of this world, and cream that you spooned.

Sometimes she had a baked stuffed mackerel or a plain shad - it made no difference, it was always the best you ever ate anywhere.

Because she was a Group B you could have plopped her in Butte with a sack of pig's knuckles and in an hour or so you would have had a feast. Wherever she spread her table you found two stars and well worth a detour. (I mean those oldtime restaurant stars when two stars means better than anything in Washington.)

She was not without guile, of course. It took her five years to negotiate the creame. Mr. Traherne taught some subject or other at a school and he had a Jersey cow.

Five years of courtesy and small attentions and behold, she could buy cream from him.

The ordinary Group A consumer could never stay the course or live so long to raap the great reward. But when my mother-in-law set her mind on cream, she got it.

"And shall not grace find means?" asks the poet Milton in one of his supreme passages. It always reminded me of my mother-in-law's grocery shopping.

She found the means of cream. And of orange cakes. And of butterbeans and corn. There were tiny squashes, infant string beans, barely laid eggs, wine jellies quivering just short of collapse, while the town around her was mere mush and burnt. Except Charity's house. She was a Grade B, too, but then she had nerve, and if the butcher didn't do right, she got a cleaver and cut it herself.

All this came back to me with the Montcalm coffee. Earlier that very day I had had coffee at the Cumberland, which is one of the few places in London you can get coffee as bad as an American bus stop.

When I drank the great cup, it almost switched my group. But then I fell back, and settled once more into indifference and courage and cynicism.

One great coffee does not a Goup B make.

And in the past few days I have, as always, eaten whatever gloop the office machines dispense, or whatever came my way. Without hope, without anger.

Only today I was drinking the "coffee" from an office machine and a reporter nearby said, "Want some cream?"

"You carry cream around with you these days?" I asked. Not really surprised. Not at that one.

"Sure." And he reached into his investigative sachel and got out a whole quart of cream. You had to spoon it.

It helped the coffee. Needless to say.

Most of us somewhere got going wrong. It has always been possible to eat well. The old woman in the town who knew where to get the vegetables, the great veal, the Jersey.

And here, not 10 feet from my desk, is a fellow who carries around Devon cream with him in a sack.

I would have always said it's not possible, in this day and age, if you're just a reporter, to eat well.There is not time, there are not resources.

But there was another reporter - of course it was a jolt - who carried the quart of cream around with him. Probably got if from the same Mr. Traherne by mother-in-law did. Don't ask me what he does to keep it fresh. Probably drinks it all within four hours or something and starts fresh the next day.

It's not time and it's not resources. It's being Group B. Born to strawberries (Fairfax, not Blakemore - only the really great strawberries will do for Group B).

Lord, my heart is turning over. I want to be a Group B, too. I'm going to find me a Jersey if it kills me.