They had a special on Deer and Deer Hunting TV about this topic. It seems that all clothes are dipped in a dye that makes the colors stand out to us. However deer see UV light much easier than we do. I have never used the UV killers before, just scent soap, plastic bags, etc, but I will spray with UV killer before this season.

If I spend $10 and it only gets me one extra mature buck than its worth the money.