Decide who to trust by what they do when there’s nothing in it for them.

Behavior with an audience or an incentive tells you what someone can perform. What they do unobserved and unrewarded tells you what they are like by default, and default is what you will be dealing with over years. Everyone is generous when generosity is being counted. The useful evidence is in the moments nobody is counting.

Watch how the people around you treat someone who cannot help them, a new kid, a tired cashier, a person everyone else finds annoying. It is the cheapest test available. You do not have to run it, just notice the results.