Per Budman's point, taking out the bloodline along the center of the tail certainly helps. Also, sometimes the electric can shave the spine there and leave some fine bone chunks on the surface. Most important for me is not to have blood in the meat. I don't have a live well so have to use a cooler. I cut their gills and drag them before throwing them in the cooler. It makes a huge difference in my opinion. If the meat is pink looking vs. nice clean white....big difference. It also matters how long they are dead of course. Cleaning them ASAP vs. a day or two later on ice also matters. I've done it both ways many times as sometimes timing and travel hasn't allowed me to clean immediately .