When I was young and it was still legal to kill wild fish I killed a couple of comebacks before I knew what I was doing. They can sometimes put up a great fight and look really bright to boot. But the meat is marginal at best. One sure fire way to tell if it's a come back or not is to check the bottom of the tail fin. If it looks a bit worn there's a good chance its been digging up gravel. As far as the bucks I've gotten bucks that look dark but still have nice red meat. With the way fishing is now I never have to worry about it anymore since 99.9% of all my Steelhead get released.