Regarding a topic that you never come into personal contact with, your entire knowledge of it throughout your life will be media-mediated. How, then, would you ever learn what you had been misinformed of?
How often do you learn new things later that, even as transmitted through untrustworthy media, allow for clear falsification of the former media presentation?
This isn't zero but it's not very common either. Usually, the domain in question is sufficiently subtle that you can't make a rigorous prediction from an untrustworthy media presentation at all; thus, the media accounts are effectively unfalsifiable (unless you go out and seek personal experience).
> Usually, the domain in question is sufficiently subtle that you can't make a rigorous prediction
Is it really a big deal then? Experts really care about the details so they will notice inaccuracies, but does that mean that they really matter to the point that the entire notion of journalism and media itself should be discredited?