I also saw this scatter plotting that you described, and for Fox News, it is more of a swing / crap shoot. Another media watchdog organization called Poynter used to have a media bias report and ultimately deemed Fox News reliable for any coverage besides politics.
To get around this, we can utilize a whitelist/blacklist of news sites. For sources of information not on those lists, we as the mods can refer to the Media Bias Chart from Ad Fontes. For sources of information not measured by Ad Fontes, moderators may use personal discretion.
Example: yesterday someone posted a link from pinknews.com, but I couldn't find it on the media bias chart. That's fine. The headline seemed like credible news, but from a queer news source.