I think camo is very effective.
People just use it wrong. They stop by McDonalds and eat a cheeseburger on the way out and drop ketchup on it. They walk ridgelines, make noise and talk. They wash their camo with detergent that uses brightners in it. They move around alot on two legs and dont lay quiet. Humans smell like Bigmacs, coffee, exhaust fumes, dogs, cats, shampoo and laundry detergent. They do not cover their faces or hands. They do not use cover and concealment.
But its all the camo’s fault right?
There are other problems such as road systems = man. Most people do not get far off of road systems.
People suprise Bigfoot all the time. If we didnt? We would never have reports or the PGF to point to. Animals of the forest have a greater awareness than most humans. Most. Our senses are bombarded daily by neon signs, car horns, trains, jets, TVs, Iphones....a million distractions all competing for our attention. Humans cope by shutting most distractions out and only focus on the ones that matter to us.
In the woods its different. You can be a sponge and soak it all in. Its a never ending game of seeking food while avoiding being eaten. What made the pine squirrel angry? What flushed the quail? The whitetail deer? A human can use the senses of other animals as well as our own.