I would have to agree.... but with a bit of elaboration... The reflections of certain colors "of" the white light spectrum are how we see color. We all remember the colors of the spectrum, ROYGBIV; Red, Orange, Yellow, Green, Blue, Indigo and Violet. We see white when all colors of the white light spectrum are reflected(this is why white clothing keeps us cooler) and we see black when all the colors of the spectrum are absorbed(which is why black stuff gets sooo hot). The cause of something having color is within its own properties...but due to the light it is seen in is the way it is seen. Water filters out the red color in the white light spectrum up to uncertain depths of 3-15ft. So if a line is red its absorbing all other colors of the spectrum and reflecting red. If this line is deep enough for the water to be absorbing the red color of the spectrum the line would be absorbing all the rest of the colors of the spectrum and reflecting nothing. Black objects absorb all the available colors of the spectrum and reflect none. Black objects aren't invisible.. are they? So your cajun line would appear close to a black color. As far as the red hooks go I totally agree... red is an awesome color for bass keying in on spring craws. But the color red will start to appear black past a certain depth. This depth is affected a lot by light quality and water temperature. Did you know humans see in shades of Green, Blue and Red.. just like the color adjustment on your TV's and monitors... But bass only see in Green and Red.... shades of blue would appear gray to black to them. I hope I've either enlightened you or aggrivated you... lol I'm no scholar... all of this was learned from an In-Fisherman article early last year, titled "Red Tackle Revolution". Very very interesting article.. Anywho