NEW YORK (CNN/Money) - U.S. investors, learning every day that some of the same companies that swept them off their feet in the 1990s were cheating on them all along, are so jaded they're even starting to wonder if the '90s economic boom, a rock-steady source of comfort, was a big lie, too.

Well, it wasn't ... mostly.

The longest economic expansion in history? That was real. The four straight years of gross domestic product growth (GDP) above four percent, the longest such streak since the 1960s? That was real, too.

Nobody can take those numbers away, because even massive, multi-billion-dollar accounting improprieties such as those at Enron, WorldCom and Xerox have little or no impact on real, live economic numbers like GDP -- for one thing, the government doesn't pull its data from corporate earnings statements.

And even if they did have an impact, such scandals would be a drop in the ocean of the $10 trillion economy.

"Not only are these numbers small compared to the economy, they don't reflect actual errors in reporting the sales of actual goods and services," said Michael Englund, chief market economist at Standard & Poor's. "WorldCom, for example, wasn't overstating the amount of phone service it provided."

As is now widely known, one thing that was fake about the 1990s was the stock-market bubble that blew up around the technological revolution. That was fueled, in part, by earnings reports that have turned out, in many cases, to be the products of creative accounting -- not lying about sales, but trying to obscure expenses.

"The problem was that we had earnings growing at a high multiple of economic activity, and that wasn't right," said Anthony Chan, chief economist at Banc One Investment Advisors. "There was a considerable amount of pressure for companies to exaggerate economic activity, but the economy was doing just fine."

While actual incidents of corporate fraud were relatively few and far between, most observers agree, "aggressive" accounting practices were a little more widespread.

Companies will now have to be more conservative in their accounting, and greater scrutiny by lenders and investors could hamper some small firms from raising capital. That, in turn, will slow down growth at the margins of the economy -- but even that effect could be short-lived.

"Banks, bond investors and equity investors will ratchet down their idea of what's normal and acceptable as far as earnings and cash flows go," said Robert MacIntosh, chief economist and portfolio manager at Eaton Vance Management.

Soaring stock prices in the 1990s were also based, in part, on the hope that the tech revolution would turn the economy into a perpetual growth machine, with GDP expanding at a whopping 5 percent per year forever without creating unemployment or inflation, all of which would drive corporate profits into the stratosphere.

In March 2000, the Nasdaq hitting 5,000 seemed like a mere stepping-off point to Nasdaq 10,000 and beyond.

"We had a few years where we thought we could grow at enormous paces and with enormous productivity -- it was a new paradigm," said David Kotok, chief investment officer at Cumberland Advisors in Vineland, N.J. "Some of that was true. The rest was fluff, and the fluff was what built the stock market into a bubble."

But that's not to say that the boom of the '90s will lead to a crash in the '00s like the boom of the '20s led to the depression of the '30s, according to Joel Naroff, chief economist and president of Naroff Economic Advisors in Holland, Pa.

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Instead, Naroff compared the '90s boom to the speculative rush that greeted the advent of the automobile early in the 20th century. At that time, companies sprang up like weeds to take advantage of a hot new market. There was a stock market bubble. Then the bubble burst, and most of those companies disappeared.

But the automobile lived on, and many of the technological innovations and new industries created in the 1990s -- yes, even telecommunications -- will survive, too.

"There are seminal points in economies, and they're reached rarely," Naroff said. "We reached one in the 1990s, and we will not go back to an economy that bears any resemblance to the one before."