I have pictures of my brother and my son in the bushes wearing opti-fade camo. I have to look real hard to see them. I also had to look real hard to see them when I took the pictures. To me, it stands to reason if I have trouble seeing them, deer and elk will also have trouble seeing them. It’s also true that movement gives you away. And moving in bright sunlight makes it easier to see than if you stay in the shadows. If you get skylined it doesn’t matter what you’re wearing. Also, doesn’t matter what you’re wearing if you get up wind.
That being said, I’ve shot a few mule deer wearing blue jeans and a green plaid shirt. The Goodwill version of camo.