At least one of the guys behind the counter will get very upset with you if you fail to separate his brass from your own. He will roll his eyes, dress you down, accuse you of not being able to read, and stuff like that. Their treatment of me when insisting that I pay them for the privilege of sorting brass is why I will never set foot in there again.
So, you brought your own ammo but then decided to buy some of theirs knowing they wanted the brass returned from the Zero brand and you failed to separate it and got upset and decided to never go back?
Sounds like a win, win situation for both parties...