I'm not too sure what any of this has to do with Amphilophus, such as "red devils"?
Now we have people posting vids of their RT's? lol
For some unknown reason you decided to bump this old thread up to question the eyesight of some posters, when I have clearly shown you an example of a "red" Amphilophus citrinellus. And that fish of Scott's that is as red as the red ruler laying next to it, was only one generation removed from the wild. (F1) Now imagine what someone with the genetic know how could have done with that male, and a female that carried the same red gene, perhaps a specimen such as the fish that Modest Man caught in Hawaii. In several years of selective breeding someone could have easily developed a line of citrinellus that consistently produced red specimens. With enough dedication and time, perhaps even blood red, such as some of the midas from the Ren Mein line that was produced in Malaysia years ago.
In nature these color morphs are rare, no question about that, so breeders manipulate genes by crossing different species as a genetic short cut to success. That doesn't mean that one can't reach the same point by using pure specimens. As an example, take a look at the following 3 recent imports by Jeff Rapps.
Clearly all three of those fish have red markings on them. Which means that in Lake Nicaragua the chances are rather good that there are Amphilophus that display even more red, perhaps more than any westerner has ever seen. Collect those fish, and work with them for enough generations, and there is no doubt in my mind that eventually a strain of solid red fish could be produced.
Is it worth the time, effort, and $$$ to breed such a fish? Probably not in most breeders minds, which is why no one has ever seriously persued it. Even the Ren Mein line seemed to have died off years ago in a part of the world where these types of fish (and in this color morph) are fairly popular.