Five years ago, when I covered David Petraeus' triumphant visit to Capitol Hill after he salvaged the war effort in Iraq, I likened the reception he received to that of conquering generals of Rome, who were feted with laurels, purple robes, trumpets and animal sacrifice.

If anything, Petraeus' reception may have been superior to the ancients', I wrote, because he "didn't even have to endure, as Roman generals did, the slave holding the crown over his head and whispering in his ear: Sic transit gloria mundi. All glory is fleeting."

In retrospect, that might have been good preparation for Petraeus, who has now seen both irrational extremes in the Washington continuum – hero and goat. Just as he was worshipped blindly then, he has fallen from grace because of an equally disproportionate reaction to a personal failing.

Petraeus resigned as CIA director because an FBI probe uncovered an extramarital affair with his biographer. Lawmakers are demanding to know why the FBI didn't tell them sooner.

Yet the investigation has found no smoking gun – just a few steamy emails.

President Barack Obama said he sees "no evidence" that national security was compromised, and there's no serious allegation that the affair harmed Petraeus' spy work, so it's baffling that the director of national intelligence suggested, and the president accepted, Petraeus' resignation.

In truth, Petraeus' behavior doesn't even merit the label "scandal." L'affaire Petraeus lacks every element of the definition.

For those too easily scandalized, let's review what makes a Washington sex scandal:

It's illegal, or of dubious legality. Eliot Spitzer, a.k.a. Client 9, had to resign as governor of New York because he and the woman he met at the Mayflower Hotel got swept up in a prostitution sting. Idaho Republican Larry Craig had to resign from the Senate because the man he interacted with in the neighboring restroom stall was a police officer. Sen. David Vitter, R-La., probably would have resigned if the evidence tying him to the "D.C. Madam" had been more specific than the presence of his phone number in her little black book.

Petraeus? Nothing illegal.

It's non-consensual, or underage. Florida congressman Mark Foley resigned from the House after it was learned that he was engaging in Internet sex with congressional pages. Gary Condit and Bill Clinton rated higher on the scandal meter because the women involved were interns. Rep. Don Sherwood, R-Pa., lost his re-election bid because of allegations (later settled) that he had assaulted his mistress.

Petraeus? Consenting adults.

Fetishes or photos. Dick Morris' tryst at the Jefferson Hotel was made memorable because it brought "toe-sucking" into the political discourse. Rep. Eric Massa, D-N.Y., was doomed by his description of "tickle fights" with staffers. Rep. Chris Lee, R-N.Y., resigned only hours after he sent a shirtless photo of himself to a woman on Craigslist. It took Rep. Anthony Weiner, D-N.Y., somewhat longer to realize he had to resign after sending out photos of other parts of his anatomy.

Petraeus? He's wearing fatigues or a chest full of ribbons in photos with his mistress.

Caught in flagrante delicto. Gary Hart's presidential prospects were undone after he was photographed aboard the Monkey Business with Donna Rice in his lap. Arkansas Democrat Wilbur Mills' reign as chairman of the House Ways and Means Committee ended after his car was pulled over and stripper Fanne Foxe got out and jumped into the Tidal Basin.

Petraeus? He was so discreet he and his paramour communicated via a Gmail draft folder.

Hypocrisy or lies. Rep. Mark Souder, R-Ind., was doomed when it emerged that the family-values politician filmed an abstinence-only video with his lover, who had worked for him. Bill Clinton's lies made Ken Starr possible – and then-House Speaker-elect Bob Livingston resigned during the impeachment proceedings against the president because Hustler magazine was about to expose his own infidelities.

Petraeus? None alleged.

Money. Nevada Sen. John Ensign might have survived revelations of his affair had it not become known that his parents gave $96,000 to the family of the staffer who was his mistress. And former presidential candidate John Edwards might not be quite so reviled if not for the hush money collected from wealthy donors to keep his affair quiet.

Petraeus? His birthday present was to have been a bike ride with Lance Armstrong. If Petraeus is guilty of anything, it's the hubristic belief, endemic in this town, that he was too powerful to get caught. But in this case, what he got "caught" doing is his business and his wife's – not the nation's.

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