

Can’t speak for op but it usually adds cheek. Sans’ use was revived a few decades ago. It tends to alter one’s tone to sound slightly stuffier, like putting on a top-hat and monocle. I’ve also seen it used more randomly by younger people who recently learned its meaning.
Edit: disclaimer and use case
Hello, this is John Cleese. If you doubt that this is the real John Cleese, here is my mother to confirm that I am, in fact, me. Mother! Am I me?
Oh yes!
There you have it. I am me.