Deer need to have 2 out of3 senses to be spooked. They either have to hear and see, see and smell or hear and smell something before they spook.
excuse me if i don't agree, at all.
if a deer smells you and doesnt like it, he isnt going to wait around to see you move. maybe once or twice he will, but dont count on it. same with sight, if they see you move, they dont need to smell or hear you to spook.