It can be refreshing and revealing, and even educational, to take a contrary view of old and accepted "truths," such as the notion that the customer is always right.

Repeated again and again, some popular assumptions are accepted without criticism, acted on without examination and repeated as the gospel truth. Beware. In economics, old truths often are revealed as old errors.There still exist, for example, many trusting purchasers who believe the adage that the customer is always right. And there are dutiful companies that faithfully adhere to that philosophy and even advertise it.

But that doesn't mean they really believe it.

While not acknowledging it publicly, some producers of products and services blame customers for not having the common sense to read directions or the ability to follow the directions they have read.

Research seems to document it. "Two complaints out of three are caused by problems for which the customer is at least partly to blame," according to a research report in The Quality Review, a professional journal.

Another accepted "truth" is that the federal budget deficit is the worst ever.

John Dessauer, an investment adviser who adorns his "Journal of Financial Markets" with the slogan, "authentic developments from an untrodden point of view," feels we might be trodding over a clod in the sod.

Forgotten by all is the fact that a dollar in 1988 was worth only 48 cents compared with a dollar in 1976, he says. His point is this: A 1988 federal deficit of $155.1 billion is the same as a deficit of $74 billion in 1976.

Since the actual deficit in 1976 was $73.7 billion, he says, "the truth is that the federal deficit today is about the same as it was when President Carter took office."

That's by one measurement. By another, he says, it might be even less of a problem. In 1976, he points out, the federal deficit was 4.3 percent of gross national product. In 1988, it was 3.1 percent.