Where I fish in the midwest, I've almost always used natural colors with texas or wacky rigged worms.. the usual greens, browns, or reddish browns. But digging through my pile of colors I don't use too often, I found some bags of bright pink, chartreuce, pure white, etc, all with one or two worms missing, and then the rest of the bag just sits there unusued. It occurs to me that this is because I've never caught a single fish on those weird colors.
My question is, when or where would colors like that work?
Of course the obvious answer is 'whenever the fish want it', but I've never once had the fish want those colors. Is there some combination of water clarity, temperature, or depth that would make goofy colors more useful than other times?