With some famous people there is some general agreement on their Enneagram type (e.g., Albert Einstein, Martin Luther King, Jr., Michael Jackson).
With others, there is often a lot of disagreement (e.g., Marilyn Monroe, Adolph Hitler, some recent U.S. Presidents - Barack Obama, George W. Bush, Bill Clinton).
Some might say the reason for this is we really don't know these people. We know their public persona or how they're portrayed in whatever source(s) we get our understanding of them from. While there's some validity to that, I think it may also be a cover for some deeper issues about the Enneagram types and our understanding of them.
Now we could also claim that some people doing the typing just don't have a good grasp of the Enneagram types yet. However, the so-called experts of the Enneagram types, the teachers and authors, also don't agree on the typing of certain people. What could be said about that is that there are different interpretations of the types. Not everybody is seeing each type in exactly the same way or they're simply noticing different things. I think this is getting closer to the truth.
Many Enneagram type descriptions include personality characteristics and behavioral traits, but are the types really about this? If personality is unique for each person and Enneagram type is only one of many influences upon personality then could two people of the same type fit the same personality description? Some people might identify with some aspects of the description while others might identify with different aspects. People also might identify with aspects from more than one Enneagram type. It seems both these things occur for many people trying to type themselves. The question to explore then is what exactly is Enneagram type if it's not personality? At least that's the question I've been exploring.
Another thing that's bothered me from when I first started learning about the Enneagram types has to with the idea that we're all nine types. If we're all nine type then why is there so much emphasis on determining which type we are? It seems a contradiction in some ways. I think this also plays into the difficulty of typing people. No one really is a single type. The way I've dealt with that is to say that each person has a dominant type that is used more than the others.
So I guess determining someone's type ultimately has to do with what aspect of that person is being focused on. It could be some aspect of personality, It could be the dominant type. It could be a non-dominant type. It seems to depend upon how each person defines Enneagram type and what they're seeing when they recognize that in someone. Maybe that needs to be explicitly stated when typing someone instead of just assigning a number to a person and assuming we all agree upon what that number represents.