"I think if we knew what we were doing, we'd be dangerous," says Robert Goodman, who produces TV commercials for politicians and proves a gratifyingly forthcoming interviewee on "Political Spots," the latest episode of the trippy-zippy public TV series "Media Probes." It airs tonight at 8 on Channels 26 and 32, and it manages to take the subject of political advertising just seriously enough.

If they don't know what they're doing now--these hypesters who package political candidates and ideas, and sell them to the public like cling peaches--maybe they will know what they're doing in 25 years, when everything about the art of commercials has been data-fied and Americans may be relying on TV not just for political information, but for the actual mechanics of voting, via two-way cable. That's the scary part.

Mark Shields, the syndicated Washington Post political columnist and judiciously acerbic host for this particular "Probe," prefers to avoid panicky conjecture, however, and has in the past defended political commercials as legitimate persuasive devices, both in his column and on his Maryland public TV series "Inside Washington" (seen Wednesdays at 10 p.m. on Channel 22). In the opening of the show, he calls TV advertising "a relatively recent but now absolutely essential campaign tool."

From there, the show skips and jumps through the Brave New Never-Never Land of political spots, including some doozies dreamed up by Goodman, like the one for Wyoming's Malcolm Wallop, who gallops through one ad on horseback, looking for all the world like the Marlboro Man at midlife crisis. In another ad packing a Wallop, a cowpoke complains about having to tote a toity around on roundups, citing this as an example of onerous federal regulation meddling in private matters.

Of one ad, Goodman says, "There's some nice subliminal things happening with that spot," and a little warning light may go on in one's brain at the mention of the word "subliminal," though Goodman is probably just using it incorrectly. Of an ad for a Kentucky senatorial race that depicted a disgruntled voter shoveling manure, Goodman concedes there was criticism from the strait-laced but that "the boys around the feed store" loved it.

Goodman also is seen presiding over the recording of a symphonic, soul-stirring jingle he composed when George Bush was seeking the Republican presidential nomination, and says he regards politicians as the heroes of the mini-musical comedies he writes. Ace political ad producer Robert Squier is also interviewed. "I dream about media," he says.

The program is nimble, swift and, in a mere 30 minutes, impressively comprehensive, although a section on attack ads that backfired should probably have included Tony Schwartz's famous girl-with-daisy anti-Goldwater spot (though maybe that's been invoked enough elsewhere). The sublime and the ridiculous are well-represented, from a Gerald Ford feelgood campaign that Shields says almost won him reelection ("Hello, I'm Tony Orlando, and I'm feeling good about America") to the adventures of Kentucky Gov. and Mrs. John Y. Brown (Mrs. Brown being Phyllis George), who sashayed into a coal mine to prove their down-to- (or even below-) earthiness. "It really makes a fella feel good," glows a miner.

Ohio Gov. James A. Rhodes is seen in one spot conducting a high-school orchestra and chorus in "The Battle Hymn of the Republic" with the unfurling of a huge American flag as a finale. Politicians--don'tcha just love 'em? Maybe our best protection is that no matter how sophisticated the high-tech marketing techniques get, most politicians will remain cornballs and bumpkins at heart.