Nearly all people seem to wear a facade, and when under stress they reveal their true nature. Perhaps they are afraid of who they really are, and its subsequent revealing to others. For whatever reason, even though their true natures are revealed in stressful situations, they arrogantly and steadfastly insist on resuming the mask after the stressful period has passed.
This is why people in general cannot be trusted. You really don’t know the person and whether they really agree with what you might discuss with them. Many veneers can be used, in an attempt to "get along", and so from person to person a different veneer, or facade is seen. When a person says he knows so and so and another person says, "that person is nothing like that.", it very may have been true at the time each person had met and talked to the person in question.
Don’t assume knowledge of anyone. The knowledge held may only be of the facade, the false front that is displayed at the time.
I know someone who has fooled me for over 45 years.