Just because I feel like arguing, I don't think a whitetail's sense of smell is its number one defense. I think it's vision is numero uno.

We can neutralize their sense of smell by the very simple measure (although granted this doesn't sell product for the hunting gear manufacturers) of staying downwind of the deer. Doing so converts the deer's sense of smell into a zero. Their hearing is great, granted, but truthfully all a sound typically does is raise their alert level - put them to sniffing and looking. Only after their nose or eyes confirm what their ears tell them do they run, usually.

Their eyesight is the rub. They are absolutely keyed in to movement, and we can't shoot without movement, right?

Again, I'm just being argumentative, but all this is triply true when you do a lot of still hunting. In still hunting, it's their eyesight that busts me the vast majority of the time.