If your friend is hunting squirrels and leaving them lay he is being unethical, because he is only hunting them for the thrill of killing them.......sick. If he was eliminating them because they were pests or nuisance animals, then leaving them lay, while not the best thing to do, would not be as bad. In states where squirrels are considered game animals and have seasons and bag limits, leaving them where they fall is not only unethical, but many times illegal. While most hunters enjoy the hunt, the kill is not the climax, only the end. Folks that hunt just to kill are killing for other reasons that the hunt itself. Kinda like spanking your child. Are you doing it for discipline or just because you like to inflict pain on others?