I never said that "decoys" in general wouldn't work, but having the same decoy in different colors and trying to determine which color worked better was not going to work.
Although I have no use for a decoy, kill lots of coyotes without one, they have become popular, although I still think it is another "thing" that's simply not needed to killed predators! Such as scent blocker, scent bomb, just a waste of money!