You can only trust things that can be proven, with the proof itself able to be verified. Sort of like the scientific method applied to everything in life. Be skeptical, and realize that everything you think you know are only things that have not yet been proven false by a single contradictory fact (which must itself be verified, of course).

It's not that big of a deal if you are accustomed to thinking along the lines of the scientific method... so there's that.