Well...you really can't. This is when your judgment comes in. Your Judgment is something that should be finely tuned and sharp. But even having that, you might come across ideas that sound ridiculous to you, because they demean your own thoughts. Then you must possess the other element; a very open and flexible mind. Because really, we can never know anything for sure with 100% accuracy. Much of our information and science is still in the stages of educated guesses and theory. But used in the wrong hands, this preliminary information can be used to influence the beliefs of a mass quantity of people. Diseases, Cures, Religion, Climate; an average person only knows and is influenced by what they see on regular media sources for these things.
So I'm really saying something that is common sense already. But it's not enough just to be mistrustful of things. No matter what you see or hear, don't immediately mark it as true. We are bombarded with info, facts, and opinions everyday. But obviously we don't see everything. It is up to us to use our judgment and not take everything at face value.
As usual, I want to hear your thoughts on this, so comment away!

