The only way that deciet can happen is if you do not have the knowledge to know any different, so you are relying on the person (or whatever) with blind faith. This is lack of knowledg, because you know no difference. People are decievers because at the heart of things they can't even be honest with themselves or they have their own agenda.

I trust no one, trust has to be earn't based on actions and I certainly wont beleive anything without checking out the facts first. At the end of the day if you choose to believe something that later turns out to be incorrect, you have simply made a CHOICE based on your own knowldge base at that moment in time. You then learn new knowldge and won't or shouldn't be decieved by it again, if you learn.

Everything is choice and people make their choices based on their own knowledge base at the time of making the choice.