How to tell if your news source is biased

I think this is a simple test. And no, the answer is not "If it says Fox News at the bottom right hand corner of the screen," though that's also a good heuristic. But I'm trying to think of a heuristic that would apply to either side of the political spectrum. Here's how you tell. If you strongly agree or disagree with more than 75% of the commentaries or spin that you see, and find that more than 75% of the stories match your world view or are blatantly against it, it's biased. Because the reality, you see, doesn't match any set world view or political agenda and so if you have an unbiased news source you should be hearing things that confirm your hypotheses and beliefs, and things that do not, all from the same source. Some of it should fill you with that warm glow of "I knew it all along" and some of it should have you thinking "wtf?, why isn't it as I had expected?" If you're watching something and nodding your head all the damn time, with nary a pause for reappraisal, doubt, or reflection, you're not watching anything objective. More likely, you're being spoonfed a bunch of crap by people who think they know what you need or want to think. And that can be entertaining, and it can be comfortable, but it's probably not informative. Thus John Stewart, who I like a whole bunch, may just be biased. But he's not what I'd call a news source, or what I believe he'd call a news source, so that's ok. Fox News, on the other hand? You be the judge.