It is so aggravating that "Mostly Factual" makes the situation (and the many, many news sources that can legitimately be called "Mostly Factual" or worse) sound so much better and more reliable than they actually are.

I prefer my news sources to be Entirely Factual thank you very much, that should be the minimum acceptable standard of factualness. Even then facts can be still be omitted or framed in a misleading way and a lot of harm can be done that way, and that's why it's only the absolute minimum required to be credible. The fact that we call news organizations who can't even reach this basic standard "Mostly Factual" is itself misleading and that's such bullshit. It would be better described as "Only Occasionally Known to Lie And Mislead" or "Carefully Hides Some Lies Among Mostly Truth".