I never have figured out why they bother to wear camouflage and then put the international orange stuff on top of that.....
I believe the theory is that the hunter orange exploits the differences between the three color vision of most humans, and the two color vision of deer and most other mammals. But I haven't keep up with any modern studies about how well this has been implemented.
My experience is... The deer smelled me WAAAYYYYYY before they ever saw me... And when I took to tree stands, they never bothered to look up. A funny "skit" from the radio... from another forum I frequent: