This has been an interesting thread. I will share an experience I had and what I did about 25 years ago. I was hunting a creek bottom with a rifle (scoped). I got bored and climbed down to start still hunting. I approached the creek I was near and heard unmistakable foot falls as if a deer or something was walking down the creek. Since I was in a position to see down the creek I froze. I the saw a small deer, a button or nubbin buck, walking down the middle of the creek. He was NOT a legal deer (no bone showing), but I continued watching as he got farther out. I saw something pink dangling from his front and hanging as if by a thread at about knee level. Curiosity kept me watching as he would lower his head and raise it. He suddenly jumped out of the creek on the far side, and he turned his head to the right to look back towards me. I clearly saw the whole side of his head was gone and figured out that what I saw hanging down was the forward two inches of his tongue connected by a blood vessel or connective tissue. It all became clear... he was trying to drink and dying of thirst. I was appalled and I immediately shot him. Right or wrong I'd do it again under the same circumstances. I hoped that as vererinarian I could qualify as an expert witness in my own behalf. I didn't get caught, but I did take it to camp making no effort at concealment to show the "shoot them in the head to save meat, for camp meat, crowd" the folly of their ways. I would have paid the fine if I had been caught but would also have fought it in court. It is not a consideration for us bow hunters, to take head shots, but I would never do it with a gun either. I could not eat this deer because it was badly infected. I fed the coyotes I guess. I think under the circumstances it was the right think to do. I do know that deer, as do most wild critters, have a good chance to heal from a lot of things like a broken leg etc.
I cringe when I hear someone say to shoot them in the head or neck either for that matter. The boiler room is the target!