You can tell a lot about a person by the way they treat their pets.
You can tell a lot about a person by the way they treat their subordinates.
But personally speaking, you can tell a lot about a person’s nature if you pay particular attention to their bathroom etiquette. I don’t mean their hygiene habits, though god knows you can tell an awful lot about a person based upon those…shudder. No, I mean how they use the bathroom, how considerate they are of others if the bathroom is shared and so on.