WHAT DO YOU tell yourself when a television show you have praised to the skies is almost totally ignored by everyone else? The easiest answer is that 1,100 homes in America are peopled with lazy good-for-nothings. Those 1,100 homes are the ones chosen by the Nielsen rating service to decide the fate of all television programs.

Unfortunately, they get their way. And we get their way. And so, most recently, a high-class, bright and polished, attractive and entertaining special, The Ford Motor Company's 75th anniversary "Salute to the American Imagination," got watched by almost no one in those 1,100 homes - and therefore, the statisticians and computers insist, got watched by almost nobody in the country.

If the figures are true, and we have been given no choice by the broadcasting industry but to take them as gospel, "Imagination" was to some extent the victim of malicious scheduling. ABC's unbeatable Tuesday night lineup of tot schlock and titillation was pre-empted by a baseball game that week, so ABC decided to move its Tuesday night to Thursday night. The folks at Ford and CBS found out about this two weeks ahead of their air date - that their competition would be the toughest in all of a week's TV. There was nothing they could do but pray the public wouldn't realize "Happy Days" and that other junk could be seen on Thursday.

Unfortunately, ABC has more viewers at its disposal than any other network on most given nights, and it also has the most zealous and efficient promotion department. The word got out. Ohhh, brother, did it get out. The CBS promotion department didn't exactly get behind "Imagination" at full tilt, either. The show had many promotable elements, but CBS was busy beating the drum for its line-up of weekly shows like "The American Girls" and "Flying High." ONce there was a way to get back home, as The Beatles told us, and once CBS was a network that prided itself on maintaining a certain dignity.

Ford sank a bundle into that anniversary show, and the company can't be happy with the results. A week earlier, a thoroughly execrable ABC special, the General Electric Company's "All-Star 100th Anniversary Show," drew much larger audience with such attractions as that defiantly irredeemable twinkling clod Suzanne Somers and a fit of lachrymose flag-waving banality. There are no two ways about certain things; the Ford show was an imaginative beaut, albeit with its ponderous or strident moments, and the GE show a piece of trash.

What's a television critic to do? If television viewing is totally habitual and if excellence really does count for nothing and if those 1,100 homes really are filled with viewers who are unwilling to experiment and watch anything but the ordinary, is there much point to reviewing and previewing television shows?

I once asked NBC vice president Paul Klein what function TV critics serve. He said. "None." TV networks don't do handstands and jump through hoops over good reviews the way movie companies do when Rex Reeds goes all a-gush, because TV reviews are not bankable. Somewhere in this sometimes frighteningly diverse little nation of ours, some crank at some publication or radio station is going to love Movie A, and thus supply the film's distributors with a marketable quote.

About the only time television critics have much influence is when a majority of them across the nation, including the two big weekly news magazines, concur that a certain upcoming TV program has so much redeeming social value that it would be bad citizenship and slightly immoral not to watch it. One wonders if the ratings for NBC's "Holocaust" would have been so high if not for the hugh press push that preceded it.

The advantage that movie and theater critics have over television critics is that they know there is a hard cult of appreciation where they can address themselves to, at the same time they provide a guide for the general audience. People have more respect for entertainment they have to pay to see, while they may think nothing of squadering an evening on lousy television, so long as it does not actively offend or antagonize them. If there is a hard-core cult of true television conoisseurs out there, it has to be one of the most select groups in the history of the world and its media.

It's quite possible to admire a movie of a play without actually "liking" it; you might say, "Well, that was interesting, but I didn't find it particularly entertaining." However, people expect everything on television to be entertaining. They expect sports to be entertaining, and news, and the weather - which is why we see the man in the funny hats doing it - and by and large they are totally unconcerned and totally unaware of producers and directors who are exercising the medium or exploring its possibilities.

You go to television the way you go to the tap for water; you expect the very same thing to come out every time.

It used to seem that bad television drove out good. "Happy Days" is pretty bad television; it's fuzzily filmed and not essentially video. It's an illustrated radio program, like most situation comedies. The content of Mary Tyler Moore's new Sunday night variety show on CBS is hesitant and thin, but the style at least attempted to tinker engagingly with the possibilities of live-on-tape TV. To the home audience, this counts for absolutely nothing. The program is such a bomb that CBS is taking it off the air so the producers can completely remodel it.

Perhaps they can get Suzanne Somers as a guest star.

A wised-up audience of television generation videastes is evolving. It has to when kids in elementary school are given access to studio hardware and allowed to make their own videotapes. There are such things as video artists who use the camera and the picture tube for pure visual expression or experimental larks. If we could just infiltrate a few of those 1,100 Nielsen homes with people who want television to be, occassionally, something other than the media equivalent of an after-dinner drink or a pre-bedtime massage, there might be more television for people who really love TV.

And then programs like George Schagfer's "Out Town" and Gary Smith and Dwight Hemion's "America Salutes Richard Rodgers: The Sound of His Music" - both recently repeated to a miniscule viewing audience - would attract people who get off a well-made TV show the way theater buffs relish a fine play or cinemaphiles a fascinating film, even if it isn't universally "accessible" or clear as a Windex-treated windowpane.

In the meantime, people who persist in the thankless tasks of loving, defending or finding some wayward hope for TV will have to plod on in patience, keeping in mind the discouraging fact that in television, quality and popularity sometimes have no correlation whatsoever.