I'm getting more into natural colors and find them to work very well in certain waters I fish. Other waters I need to go with brighter, less natural colors. Not only is water clarity a part of it, but water color can make a difference. Part of that is light penetration and dispersion, but another part is that fish see color differently than we do. I'll have to look up the one study an aquaintence worked on, had to do with color vision and visual cues in fish. (specifically cichlids, but principles applied to all fish)
One of the waters I fish is dark and tannin stained, but the water is clear (not a lot of suspended particles). Looks about like root beer. Greens don't work in this water very well, but browns work great. Along the same lines with bright colors, orange is way better than chartreuse. And gold better than silver. Haven't used them extensively, but I would suspect purple would outfish blue on this water. A river I fish regularly is the opposite, the water ranges from clear to silty with a greenish tan tint. Greens are better than browns. Pretty basic stuff, but it seems a lot of people dont think about it. Reds and whites seem to do well everywhere for me.
Something else people don't always think about is that fish don't follow just color in visual cues. Pattern plays a big part, maybe a bigger part than color due to the variability in color caused by genetic, seasonal, or environmental effects. So if the color isn't natural but follows a natural pattern that the fish would prey on they'll likely hit the bait.