We are told:
וַיֶּאֱהַב יִצְחָק אֶת עֵשָׂו כִּי צַיִד בְּפִיו וְרִבְקָה אֹהֶבֶת אֶת יַעֲקֹב(Gen. 25, 28). Yitzhak was an honest individual and he could not imagine that anyone would lie. When Esav wanted to impress his father about his religiosity he would ask questions about Jewish law. Yitzhak believed he was sincere and he was able to love him. Rivka, on the other hand, had grown up in Lavan’s house and she knew what deception was. She thus saw through Esav’s fraud of his father and could not love him. She saw the honesty of Yaakov and loved him.
It takes a bit of wisdom to see through the charades of people. We must give everyone the benefit of the doubt but should not be so believing that we are easily deceived.
There are some people who can lie with a straight face and can, as the expression goes, sell you the Brooklyn Bridge. While we should not suspect people when we have no reason to but we should be careful with whom we deal. Just because we are honest does not mean that everyone is.