I know a lot of people who are compulsively truthful. They cannot, would not, tell a lie about their age, their children or who cut down their own emotional cherry tree. Nevertheless, it has begun to occur to me that these same people will, without a moment's hesitation, automatically fib about two things: how long it takes them to drive to work and how much they paid for their house originally.

They are, I hasten to add, sinners of ommission, rather than commission. The friend who swears that he gets from his distant suburb to his office in 28 minutes flat isn't really lying. He is, rather, editing reality.

It does take him a mere 28 minutes to get to work if he times his test run for a dry midnight, presses his stopwatch at the tollbooth instead of the garage and discounts the stall-and-crawl, mope-and-hope traffic from the freeway to the parking lot.

In the same spirit, the person who tells me, gleefully, what his house cost in the good old days is also within the letter, if not the spirit, of the truth. As you wander through his home, he will tell you what he paid for it. But not what it was exactly he paid for.

Let me explain. I know a man who bought his multi-gabled Victorian in 1962 for a mere $21,500. He has informed me with restrained glee that he could sell it now for $100,000. What he did not mention, as I exclaimed over the wainscoting and the circular staircase, is that in 1962 the house was heated exclusively by two wood stoves. What he also did not mention is that the house came with only one bathroom, which had been designated a national historical monument.

The fact is that, since 1962, the man has "improved" his home enough to truly break even, minus real estate commission, if he sold out.

A woman I know gives dinner guests informal tours of her charming, rambling country home. As you pass thrugh the entertainment wing and back to the dining room, she will casually let it drop that she paid $33,000 for this exquisite multi-sectioned home, back in the late '60s.

She will not, however, casually let it drop that this was before the entertainment wing, the garage or the new wiring. These added extras were, well, added extra decimal points to the original cost.

Her brother's home was bought, as he tells it, for the cost of a mere shell today. But it was, I have discovered, a mere shell when he bought it. A mutual friend insists that it had been used as a set for a documentary on the firebombing of Dresden. He had, in fact, restored it with his own private Marshall Plan.

I am aware of this widespread human flaw, because I am guilty of it. When I tell people how I bought my home for a mere pittance six years ago, I seem to forget, and certanly forget to say, that there was something missing back then.

What was it? you ask. Let me think. . . . Oh yes . . . It had no kitchen. Nor any downstairs bathroom. Nor a finished basement. Nor, if you absolutely must get picky about it, a second bathroom upstairs and an office on the first floor.

Since it is worth three times what I paid for it, I will no doubt someday make a fortune, if I do not add the minimum wage for my labor.

Why is it that decent human beings like us who do not cheat on our income tax or exaggerate our childhood report cards fudge our real-estate balance sheets?

Because we want to be seen as persons of rare intelligence, foresight and acumen. The quickest way to establish yourself as a genius in this society is by proving you carried off a piece of financial wizardry.

But the only wizard the middle class is likely to see is the one in the roof over its heads. And never mind that it isn't the first roof on the house. So we tend to "forget" what we put into it and brag about what we could get out of it.

There is another reason. The way to insure our investment is to make others lust after our mortgage. We lure the next generation down the path of happy homeowning by pointing out profits rather than pitfalls, or gutters, roofs or siding.

This is a minor, even off-white sin -- undoubtedly expected in the market -place of human fibs. After all, if we're not homeowning for the investment, we would have to other virtues to advertise. Except, of course, we do live awfully close to the office.