Takeaway: Fox News not only lies a lot (surprise, surprise), but it's lying more now than previously -- that is, since PolitiFact last did this survey, in September 2013. (MSNBC and CNN lie less, and are lying less then previously).
At Fox and Fox News, 10 percent of the claims we’ve rated have been True, 11 percent Mostly True, 18 percent Half True, 21 percent Mostly False, 31 percent False and nine percent Pants on Fire. That means about 60 percent of the claims we’ve checked have been rated Mostly False or worse.At MSNBC, 44 percent of claims investigated were found Mostly False or worse; CNN was the best of the bunch, with 80 percent of claims found Half True or better.
The article includes a disclaimer of sorts:
As we have said in the past, be cautious about using the scorecards to draw broad conclusions. We use our news judgment to pick the facts we’re going to check, so we certainly don’t fact-check everything.PolitiFact is considered to be generally nonpartisan, but both left and right howl with indignation when a "fact-check" goes against them.