[Gene_Parmesan]

You used the term "biased," not them -- just to be clear. Which way a publication leans can be determined by things that have nothing directly to do with integrity or truth telling -- which stories they cover, for instance. In practice, lean often comes along with audience. Like any publication, news outlets have audiences, and the interests of that audience group will determine what stories it covers and how it covers them. This can be done with full journalistic integrity; in fact, it's harder (and perhaps impossible) for a publication to have zero political lean.

Political lean != acting as a mouthpiece.

Do also please note that your personal political leanings will determine whether you view the reporting of any publication as unethically biased or not. No matter which sides we're talking about, what one party reports as truth, another will hear as politically motivated.