Washing machines try real hard to agitate and get the dirt out of the clothes. I use gentle cycles , wash inside out ( like Darla has said:)), scent free detergents and air dry whenever possible. I also store them in a big airtight tub that I throw a few handfuls of leaves in there for cover scent.
After hunting, I leave my exterior clothes outside and wash only after a month or so, unless I get blood all over something:D.
If the fading is too out of hand, contact the manufacturer for a replacement, many in the hunting business are good about stuff like that.