A lot of the answers here recommend observing a person when they're hungry or tired, or even intentionally provoking them/depriving them in order to see their “true” personality.

This approach is bullshit.

You can do this to people, but all you’ll be seeing is them at their worst. Not their best personality and certainly not their “true” personality.

I’ve known a few genuinely kind people who become awful to be around when they're hungry or tired. What does that mean? It means they aren’t used to repressing their body’s signals to eat or sleep. How does that make them bad people?

You can't know someone’s “true” personality, because you can never fully know someone else; there will always be parts of themselves that they keep from you intentionally, and other parts that even they might not know exist.

The only thing you can do is take a chance and spend time with them. The more time you spend with a person, the more you interact, the better you get to know them. It's that simple. There are no shortcuts. - Matthew Manning, Quora,