The original quote, boiled down, is a statement of personal preference, not a statement of fact.

I like Coke. You like Pepsi. Who's right?

But back to facts for a moment. Even when a source may be biased or lying, the truth still isn't based on what he or she *says*.

It's based on independently observable facts.

The future of a tax is not a fact. It's a prediction or a promise. Predictions and promises aren't facts: at best they're opinions, or statements of intention, and at worst they're lies to get your support. If I say, for example, "Elect me and I'll revoke Obamacare," maybe I will and maybe I won't. If I say, "With a stroke of this pen I, President Palin, will revoke Obamacare in the next ten seconds," it's still just a promise, albeit one likely to be fulfilled.

If you believe that a fact is are indeterminate, that in itself means you're thinking independently. You don't need the source's name. Of course, when it comes to a factual claim, you'll be safer in distrusting an unidentifiable source.

The truth of a fact is independent of the person who asserts it. If I feel the raindrops, or if I don't, it doesn't matter what GWB or President Palin says. What matters is feeling the rain.

If it's expert knowledge you want ("Space aliens are real!" "Space aliens aren't real!" "Maybe space aliens are real!"), you may have to choose from disagreeing experts (including self-proclaimed fake "experts"). But that has nothing to do with the reality or unreality of space aliens. They're real or they're not, regardless of who says so. It just means that maybe you'll choose the wrong expert.