Delta Airlines, you might have noticed, does not run negative TV ads about USAir. It does not show pictures of the crash of USAir Flight 427, with a voice-over saying: "USAir, airline of death. Going to Pittsburgh? Fly Delta instead."

And McDonald's, you might also have noticed, does not run ads reminding viewers that Jack in the Box hamburgers once killed two customers. Why? Because Delta and McDonald's know that if the airline and fast-food industries put on that kind of advertising, America would soon be riding trains and eating box-lunch tuna sandwiches.

Yet every two years the American politics industry fills the airwaves with the most virulent, scurrilous, wall-to-wall character assassination of nearly every political practitioner in the country -- and then declares itself puzzled that America has lost trust in its politicians.

Voters declare a burning desire to throw the bums out. Polls show an aversion to politicians that can only be called malignant. And the sages pull on their beards, stumped.

The economy? It is in better shape than it has been in years.

Gridlock? People so thoroughly disgusted with their politicians want gridlock. They approve of a system that promises to stop them before they legislate again. It is not the system they dislike. It is the players they cannot abide.

Why? No need for exotic theories. The simplest explanation is always the best. Politics is the only American industry whose participants devote their advertising budgets to the regular, public, savage undermining of one another. It is the only American industry whose participants devote prodigious sums to destroying whatever shred of allegiance any of them might once have won with their customers.

Compare. About the only other business that indulges in negative advertising is the long-distance phone business. MCI tells you that AT&T overcharges. Not so, says AT&T. This piddling stuff is about as nasty as it gets.

Moreover, picking a long-distance operator hardly demands a relationship of trust. Whereas picking an airline that suspends you in a sealed aluminum tube at 30,000 feet is a matter of trust. So is picking a fast-food restaurant that presents you with heavily camouflaged meat confected by a 16-year-old with acne. So is picking a politician, who rifles your paycheck and regulates your life. Yet only the politicians work systematically to kill that trust.

Turn on the tube and watch what one candidate -- any candidate -- has to say about the other. Then remember that no matter who wins, one of these miserable, execrable human beings will end up representing you in Congress.

Sen. John Danforth of Missouri recalls that in his first Senate race in 1970, he ran against the popular Stuart Symington and lost. Yet both ran such positive and honorable campaigns that Danforth ended up one of best liked politicians in Missouri. Six years later he ran again and won.

That was a long time ago in a galaxy far, far away. (Danforth is retiring now from a political environment turned toxic.) The politicians have since "gone negative." The reason is simple. Negative works. It gets individuals elected. Add up all the individual acts of political homicide, however, and you have a political class that is collectively committing suicide.

The basic theme of the 1994 campaign is that everyone running is a liar, a cheat, a crook or a fraud. Take the, oh, 3rd District of Tennessee, Button vs. Wamp. Wamp portrays Button as a fraud. Button calls Wamp a liar, and compliments Wamp for "kicking {his} chemical dependency." A nice touch.

In the most publicized case of mutual assured political destruction, the Virginia Senate race, Oliver North's TV ad starts with "Why can't Chuck Robb tell the truth?" which Robb's answers with "After lying about President Reagan and even lying to schoolchildren, now Oliver North is lying about Chuck Robb." To schoolchildren, mind you.

The immutable fact is this: As of on Nov. 9, one of these two highly advertised liars will be the next senator from Virginia. Every state in the union will be sending to Congress some brutally excoriated campaign survivor. The 104th Congress is guaranteed to be an assembly of the most vilified persons in every American community. And you thought the baseball owners were self-destructive.

Do we really need seminars on why voters loathe politicians?