if the animal is basically a fresh kill or reason to believe illegal activity had taken place. These old dead heads are not in question. This year we found a nice 6 by 6 bull fresh kill and called the game warden as it was the 1st day of hunting season for us. He came up and did some CSI work and could find nothing wrong and gave my friend the skull with rack and the paper work for transport. Sheep you still need to take in and get a plug put in the horn even if it is old. Hope this answers your question!
Different states have different rules. I know that in Utah and Arizona you can not just pick up a "dead head" with antlers attached.
In Utah you need to notify the Division of Wildlife and they will come out and investigate the site. If they find nothing wrong such as a natural death or wasn't shot then you might get the dead head but don't count on it.
In Arizona I believe that it is just illegal to pick one up no matter what. But I could be wrong since I haven't checked on it yet.
Hunting is not usually a pursuit where instant gratification abounds. It takes a lot of time, practice, resources and patience to be a successful hunter. So when someone decides that an area they hunted only once without taking an animal is worthless and devoid of game, I don't quite understand it. These people usually jump from game management unit to game management unit; trying a new one every year.
Now don't get me wrong, there are people that just enjoy scouting and hunting...