Overall, Fox News was viewed as most trustworthy by a quarter of the June 2014 sample, just beating off the combined total for the 3 broadcast networks (23%). CNN came in at 17%, PBS at 12 %. MSNBC fell below the satirical "faux-news" Daily Show, at just 5%. There were significant differences in trust among those with different political ideologies and party identifications, particularly when it came to Fox News. But MSNBC still couldn't garner support from more than 10% of Democrats or liberals.
That people's trust in news outlets is generally low is nothing new. Pew and Gallup both regularly ask about the public's trust in news media in their polling, and find trust declining, and also becoming more partisan - suggesting a perceived bias (check earlier posts here and here).
And the American left must be shocked and appalled that "rabid, extremist, right-wing Fox News" (their terms) remains the most trusted news outlet among news consumers - and remains the most-watched of the cable news outlets by huge margins. And that reliably leftist MSNBC remains among the least trusted sources for "accurate information about politics and current events," although it has managed to capture second place in viewership from CNN.
Source: Brookings Survey: The Most Trusted Name in Television News Is . . . Fox News, National Review Online