Bias on the left
We rightly mock right-wing Fox News for its "fair and balanced" claim, but the left-wing Alternet, though not making a similar claim, often shows a crude bias, like this story (Poll Shocker: Bernie Sanders Leads Trump and Bush by Double Digits):
In the latest McClatchy-Marist poll, Sanders outpolls GOP frontrunner Donald Trump and establishment candidate Jeb Bush. Against Trump, Sanders leads 53 to 41. Against Bush, Sanders leads by 10 points, 51 to 41. The Vermont senator's lead is particularly large among voters 18 to 29; there, he leads Bush 57 to 38. Even among some of the most conservative voters in the country, in the South, he leads Bush 46 to 45.
What about Hillary? When you read the poll story on McClatchy, you learn that "Bernie Sanders lags far behind Hillary Clinton in the race for the Democratic nomination for president..."
Sanders is 22 points behind Hillary, to be exact---and she would beat Trump by 15 points.