I primarily ground hunt.

That being said, I've had more than a few deer within 5'. Only once did a young buck walk up and touch my leg with his nose trying to figure what I was by smell.

Bowin' a few years back I wound up between a 300+ lb sow and her 4 cubs just before sunset. She walked right up to my ground blind within 2' of my face. I still remember the smell of her breath. Looking directly into her eyes I could tell she didn't have a clue as to who/what I was.
I did not want to kill that animal because of her 4 cubs.

-Ken