What you see as matching the backround isn't necessarly the same thing a game animal see's as matching it.
Unlike us, deer see green, yellow, orange, red, and brown all as shades of yellow because deer have no red cones.
They also see UV light that we can't see because by nature, they are creatures of the night and can see quite well at night.
It could be that even the most carefully chosen cammo patterns actually "glow" to a deer compared to the natural backround you try your darndest to match with it.
rc