So. Sansa. I hear some people think she’s not very clever. This is a view shared by several characters in the books.
But there’s no reason the readership should share those views. Sansa is a very clever individual who makes increasingly good use of several skills she started the series with, and develops greatly as an observer and an actor over the course of the story.
Putting everything under a cut, for reasons of four books of brainpower.