I've always thought red jigs would be like that Red fishing line that after a certain depth it becomes invisible. Or something like that, could be wrong too. Heck I don't know.
Heres a link that explains it better.
Red Fishing Line - Benefits of Using Red Fishing Line
"The reason for this is the spectrum of light changes as it penetrates the water. As demonstrated by this discussion, the first color that disappears as light penetrates water is red. This is why red fishing line is so effective. Red disappears at 15 to 30 feet of water. We all know that a line that is invisible to fish will not spook your target and lures look more natural. For this reason red will put you on more action in deeper presentations."