A lot of our news reports are quick summaries written up in a few minutes by a busy person who quickly gathered whatever info was at hand and not so much of the long, in-depth investigations of the past.

So... likely quite a lot. I trust verifiable sources a lot more than I trust any outlet, even the supposedly reputable ones. I mean, just how long did it take for Jayson Blair to get caught fabricating stories in the NYT? [1]

[1] https://en.wikipedia.org/wiki/Jayson_Blair