Sense, Nonsense, and Not-Sense

I don't know if they have the right to protect their colors, but they do, that much I know. I suppose that dilution of a name or product, or intent to cause confusion between products is good grounds for trademarking ("Wibsters?"). I just wonder whether those colors can/should only be trademarked within the boundaries of the logos or designs that they are a part of. Whether accurate or not, this still gives off the idea that a particular shade of the spectrum is off-limits for anyone else to use.