Ive personally not had problems with deer seeing my face from the ground. Im im quiet and the winds right, and i dont move, they are oblivious. Even when i bleat, while at full draw, at less than 30 yards, they are pretty much oblivious. I must look like the underbrush!
I have gone both ways. Usually I start off with a mask and shed it as the day warms up. The deer do not seem to care either way, of course their still out there running on the mountain.(LOL) As far as that goes I have stalked up on deer without any camo on at all (not in season however). I feel more comfortable without my face mask and for me thats reason enough to go without. For me the only animals that really seem to notice are turkeys. They bust me when I forget my mask just about every time.
I wear a beard during hunting seasons, hat, and a face mask, at times, staying in shadows, keeping a brush screen between you and the game helps, but mostly, move slowly. I aslo never make eye contact. :)
Had two does walk within 10 yds. by me last week, it was great. They are very slow and cautious animals.
Couldn't take them, it was bucks only.