Its very hard to see or really tell graps. I will say, Ive been in the wide open with no blind at all, and at less then 10 yards the deer not see me. I've also been spotted many times in what I felt was very good cover! Shooting at a deer looking at you is bad medicine,even at close range... I know that much. Id be much more concerned with swirling winds. Swirling winds = no shot or deer for that matter. Id think if the deer are spooking, its from smelling you, not seeing you. Especially doe are prone to parade around making a rukus if they just see something fishy. Id think you'd know....im very hard of hearing and I generally know when they see me. That nose is the tough one....
I know nothing is always a given in hunting wild animals. But, in killing deer over the course of 25 years, ive learned a thing or two about them. One of the biggest things, is realizing your scent lingers after you are gone from the woods. Over the course of a few days hunting an area, the deer know it, and avoid the area. They will often skirt 100 yards or even less to avoid where you were hunting. Repeated huntings will continue to lower your chances. The very first hunt, is the best chance. From there, the hunting in that spot will deminish. I try not to hunt my spots until there is high deer movement, and all is right with winds and timing. Then I plan on killing my first time to that spot. I rarely hunt the same stand site more then 3x, and I generally will not hunt the same deer more then 6-8 times, unless its a very unusual situation, where I can get more hunting done without them catching on as quickly. I dont care how careful we are, or what we do, scent is what eventually spoils all our stand locations....sometimes in a hurry!
Thats why I use to have 20 stand locations on 10 completely different properties. When I follow that, I kill multiple deer every season, and anyone can. Its just a matter if we can do that, or I suppose there may be some folks too hard headed to change what they do....present company excluded.