I guess my determination of the trustworthiness of news sources is related to the dependence on commerce and business for the delivery of the news. Advertising dollars have a strong influence on the content of "news" and the determination of what is newsworthy. Sometimes it isn't necessarily a matter of what is fact or not, but how the facts are presented. Some broadcasters, like Rush Limbaugh, Glenn Beck, Laura Ingraham, and their train of wannabees, are paid residuals to slip "news" items that are really paid propaganda into the text of their programming. Though such payments are a matter of public record, few of their listeners are probably interested in knowing where the money came from or what was paid and what was part of his actual broadcast text. Those programs aren't news sources, though.
Since moving to Pittsburgh, if I'm in the car or listening to radio, my news of choice is NPR. Most conservatives think it has a liberal bias, but really, anything that doesn't agree with their perspective is marked as "liberal." NPR is actually about as close to neutral as you can get in broadcasting. Their human interest broadcasts are pretty engaging as well, dealing with real problems faced by real people. During the day, at work, I'm usually tuned in on line to Pacifica (
http://pacifica.org.). Independent, not for profit media is the best source of factual news.