When you meet someone how do you guys figure out their personality type so quickly?
They don't. They just think they do.
Linda V. Berens makes a really good point in all of her books which teach type:
We have 3 parts of "self."
1) Core self
2) Developed self
3) Contextual self
The latter is what trips up people, and fools them into thinking they know another person's "type." The contextual self is who we are in any given situation. That means if you go to a TypeC meetup and talk with someone, you're meeting who they are in that LIMITED CONTEXT only. And furthermore, if someone thinks they can type someone from meeting them once, or even from their posts in this forum, which is another LIMITED CONTEXT, then they really are what I call a "cowboy," which is what I call people who don't know what they are talking about. They just think they do.
Jung said it took him
years (yes, you read that right) to type his patients. We have so many aspects of ourselves moving in and out of view in any given moment, both conscious and unconscious, that who-or what-you are seeing at any moment in time is highly unlikely to be an accurate reflection of one type. In reality, you could be seeing a reflection of many types all at once. We really are that complex. People don't want to hear that, though. They would rather rubber stamp a label on every Tom, Dick, and Harry, assume 1000 things about them that aren't even true, and live their life in "blissful" ignorance.
I will leave you with a comment from someone who works with Typing, for a living:
"Keep in mind that, ethically, one never tells a client what their type is—it's not even a good idea to suggest a type for them."
-Vicky Jo Varner