Side by side, the two cartoon figures stride across the screen, their stick arms wrapped around massive boxes of gifts. Mischievous music tinkles in the background and a bemused narrator—his words punctuated by comic sound effects—tells a tale of petty corruption by Colorado Congressman Ed Perlmutter, a Democrat running for his fourth term.

Congressman Perlmutter sure knows how to work the system, the narrator begins, as stick-figure “Perlmutter” and ponytailed stick figure “Mrs. Perlmutter” stride into Washington, DC. The ad goes on to describe Mrs. Perlmutter as a lobbyist for the failed solar company, Solyndra, who got paid $140,000 to lobby for the company as her husband voted to steer taxpayer dollars into its coffers. The narrator concludes: Congressman Perlmutter voted for the bill. Lobbyist Perlmutter got paid. And taxpayers got scammed.

The offbeat charm of the ad, aired by Perlmutter’s challenger for Congress, Joseph Coors, was marred by one problem: Its allegations were false.

For starters, Perlmutter’s vote in favor of the massive 2009 stimulus bill did not steer money to Solyndra; the funds were allocated by the Energy Department. Two other details, equally crucial: By the time of the stimulus vote, Mrs. Perlmutter no longer worked for Solyndra. Also, she had already divorced the congressman.

In campaign 2012, political advertisers—riding the flood of cash that Citizens United uncorked—poured an estimated $2.9 billion into spots on broadcast television. A few of these resorted to outright falsehoods. Many more, like the attack on Perlmutter, perfected the ancient art of arranging a series of true or opinion-based statements in a way that leads to a plainly inaccurate impression. In Denver, such dubious campaign ads seemed to pile up as high as the Rocky Mountain peaks that overlook the city.

The presidential race alone brought roughly $59 million in Denver airtime for more than 55,000 spots, and an industry source cited by The Denver Post estimated that more than $67 million was spent in the Denver market overall. Mark Cornetta, general manager of Denver’s most watched local TV station, KUSA, estimates 45 percent of the money came from outside spending groups, such as super PACs and political nonprofits. The “vast majority” of the spots that this spending spree purchased, said Brandon Rittiman, a KUSA political reporter, included “distortions of some kind.”

Local broadcasters like KUSA are emerging as the biggest financial winners in the free-for-all following the Supreme Court’s 2010 Citizens United decision, which allowed unlimited checks to flow into political campaigns from donors who often remain secret. Yet each misleading ad that aired also made it a little tougher for stations to do the job they were granted monopoly of the public airwaves to perform: serving the needs of their communities by accurately informing and educating voters. And as the number of ads has grown in each election cycle, the danger is that they’ll set the political agenda in the future.

How did TV stations respond to this situation? And how should they respond? It’s a question for both executives and the newsrooms of local broadcasters, which air the majority of political ads. Let’s take a closer look at the Denver market.

The corporate side: to screen or not to screen?

Ads purchased by federal candidates—even deceptive ones like the Solyndra attack on the Perlmutters—by law must be aired by broadcasters, and at a discount rate and without any alteration of their content. In turn, broadcasters cannot be held liable if the content of a candidate ad is defamatory.

But for ads by outside spending groups, the situation is very different. Stations can charge as much as the market will bear; they can be sued for defamation over the ads; and, perhaps most important, they are entitled to reject ads or demand changes in their content. Guidelines on the FCC website direct stations in general terms to “act with reasonable care to ensure that advertisements aired on their stations are not false or misleading,” but the agency says that enforcement is primarily conducted by the Federal Trade Commission. In turn, the FTC says that it only regulates product ads, and the Federal Election Commission says there is no law regulating the accuracy of political claims by outside spending groups. So even as outside spending groups’ ads have proliferated, there is no agency minding the store. Given free speech considerations, some people are glad about that.

Sasha Chavkin covers political money and influence for CJR's United States Project, our politics and policy desk. He has written for ProPublica, the Center for Public Integrity, and The New York World. Follow him on Twitter @sashachavkin.