Media watchdogs on both ends of the political spectrum coincidentally are using mobile billboards to draw attention to questionable reporting by media outlets -- also on opposite ends of a spectrum.

On Thursday, Media Matters launched a microsite and placed ads on mobile billboards circling the Palace Hotel in San Francisco where Fox CEO Lachlan Murdoch was speaking at a Morgan Stanley investors conference.

The billboards carried messages that "Fox News Lied," that "Fox Knew" 2020 presidential election fraud was false, and that "Lachlan Murdoch Helped Fuel An Insurrection."

The microsite offered more detailed accounts of revelations from the Dominion Voting Systems suite depositions that Fox execs all the way up to Executive Chairman Rupert Murdoch knew the story was horse hockey, but allowed their prime-time talent to fan the flames nonetheless (see video below).

On Friday, right-wing media watchdog Accuracy In Media used mobile truck billboards in New York City to take aim at The New York Times' coverage dismissing the possibility that the COVID-19 virus began in a laboratory in Wuhan, China, even though intelligence agencies think it was likely, though not conclusive.

What's the lesson here? It's that regardless of your political partisanship, or the media you're attacking, out-of-home media is a pretty good way to draw attention to it. And to get political advertising trade reporters to blog about it too.