Because they suggest journalists who deliver bad news for Republicans are biased. For real.
You couldn't ask for a better example than from our pals at Newsbusters who posted this dart:
Friday's CBS Evening News delivered a parting shot at outgoing President George W. Bush as fill-in anchor Maggie Rodriguez paired how a just-released CBS News/New York Times survey pegged Bush's approval rating “at just 22 percent” -- which she noted “is the lowest for an outgoing President since the question was first asked more than 70 years ago” -- with how “68 percent said they expect Barack Obama to be a good or very good President.”
How dare CBS accurately, and in a straightforward manner, report the facts as reflected by public polling which captures the feelings of everyday Americans!!