" Just think about how many times you have criticized someone else, in hindsight, for their failure to spot a liar. You should have known. There were all kinds of red flags. You had doubts. Levine would say that’s the wrong way to think about the problem. The right question is: were there enough red flags to push you over the threshold of belief? If there weren’t, then by defaulting to truth you were only being human. "

― Malcolm Gladwell , Talking to Strangers: What We Should Know About the People We Don’t Know