I think people are hard-wired to respond positively to certin kinds of behavior, which are usually classified by too vague to be meaningful terms such as charm, charisma, or confidence. We live in a social world much like the wolves, where certain people take the lead and tell others what to do.

If you tend to have a largely positive regard of a certain type of person, such a person will have an easier time disarming you. And people are most likely to be taken in by somebody like them, e.g. Bernard Madoff. The other option is to trust nobody but that doesn’t work very well either.