And mind your own while you are at it......

But this is the blind spot in human nature:  we are poorly equipped to gauge the character of the people we deal with.  Their public image, the reputation that precedes them, easily mesmerizes us.  We are captivated by appearances. . . . And so, because of our blind spot, we suffer under the irresolute leader, micromanaging boss, the conniving partner.  This is the source of endless tragedies in history, our pattern as a species.
     At all costs, you must alter your perception.  Train yourself to ignore the front that people display, the myth that surrounds them, and instead plumb their depths for signs of their character.  This can be seen in the patterns they reveal from their past, the quality of their decisions, how they have chosen to solve problems, how the delegate authority and work with others, and countless other signs.  A person of strong character is like gold—rare but invaluable.  They can adapt, learn, and improve themselves.  Since your success depends on the people you work with and for, make their character the primary object of your attention.  You will spare yourself the misery of discovering their character when it is too late.

Robert Greene,  The Laws Of Human Nature, from the chapter The Law of Compulsive Behavior