I think GB is probably right. Think about it this way. First of all, deer are not supposed to be able to see colors as well as we do anyway, so I would imagine that if UV brightners did have a blueish hue to them, it would not be very noticeable to the deer.
What is most likely happening when a hunter gets spotted, is that first he moved, and got noticed. Then once the deer key on him, it only takes seconds before they recognize the head and shoulders outline and go on full alert. If you don't believe this next time a young deer spots you, stay motionless. The young ones usually will ignore you and go about their business as long as you stay still. It's the older ones who recognize your outline, primarily the head and shoulders.
It is ingrained in their genetics to be scared of man. I believe it's just basically movement or shape that gives us away. That's why I don't believe camo is very important. To me, any old camo will do, as long as it's not extremely dark, which again makes your shape easier to recognize.