I don't understand the hostility toward these signs. It's just a private citizen asking you to respect his wishes. Don't get me wrong, I'd prefer to carry everywhere I go. But if a friend or family member asks me not to carry, or smoke, or swear in their home, I don't.
Of course I also completely support going elsewhere if you don't agree with those wishes. But I see no problem with the signs on private property.
Shoot smart. Shoot S-Mart.