There’s been loads of studies done on how and what deer can and cannot see.They see colours in a different spectrum then we do.They don’t see reds very well,which is why hunter orange is not a huge disadvantage,they see orange more as a shade of grey.They see UV and blue spectrum very well,blue jeans are about the worst thing you can wear deer hunting.
Red n black plaid jacket and black wool pants worked very well for centuries.
Camo prints with too much detail tend to just blob together at a distance but look really cool on the Cabelas clothing rack.
More open patterns such as Predator conceal movement and break up your outline better from a distance.
Waterfowl/turkey hunting is a different story,birds see colours very well,bright colourful plumage is a communication method in the avian world.
Moose have relatively poor eyesight,often as not I just wear a black hoodie weather permitting,effectively turning myself into a mobile decoy complete with fake cardboard or plywood antlers.
Winter coyote hunting,I’ve worn everything from CDN surplus all white suit,to realtree snow camo pattern,white jute Ghilliei suit,to a white poncho bed sheet and everything in between.....but reality is,movement is the key factor.Sit still,head on a very slow swivel,and they generally won’t see you until it’s too late.Legendary Arizona coyote hunter the late Gerry Blair has called coyotes literally into his lap wearing a Santa Claus suit just to prove it can be done.
I bought into the camo marketing hype for decades,going back to the Trebark days of the early 80s......nowadays I don’t concern myself so much with it and focus more on warm,dry,functional clothing......wool and liteweight,quiet,waterproof gear....but it just so happens that most of the best gear suited for staying comfortable while hunting is often only offered in camo.Good quality gear like Sitka/KUIU etc would be just as functional in flat earth/drab olive solid colours,maybe a splash of black lines to break up silhouette.......but it sells better if it looks cool.