I've always felt that the core of MBTI lies in the S vs N difference. There are many reasons to believe it's all BS but....when you observe the way people express their ideas or opinions it becomes pretty clear that there is something to it.

Sitting with family in a debate about Hunger Games vs Divergent and clearly each side isn't getting their message accross because everyone is focusing on different parts of the conversation.

I know my sister is a Sensor because when I tried explaining with an abstract example of Meat vs Bones she was genuinely confused about what I meant at all. She does understand metaphors just fine but in this whole debate she isn't processing them.

I feel that it's moments like these that highlight the various differences. Of course N vs S isn't all there is to it but some incidents like this do pile up and they are consistent about it.