[nasir]

Paying attention to the micro interactions of a person (or CEO) with others especially those who have no business interest with them can give a good view of their morality. These can be simple things like a conversation they have with random strangers and their judgement on that.

[JohnFen]

This is a bit like how, when you're starting to date someone new, you should pay attention to how they treat servers and other workers at the places you're going to.

But in the case of interviewing a CEO, you don't often have a chance to see them interacting with random people.