I look at it like this... The firearm belongs to them until I buy it. I ask for permission to do just about anything other than simply holding it. Personally I don't care if the clerk clears the weapon, I will check it myself no matter if he clears it or not. I am certainly not going to walk out of a store simply because the clerk doesn't clear the weapon in front of me, that's just a little dramatic.
Life is a web woven by necessity and chance...