yeah I've heard stories about customers in there...
my friend works in an office-depot store here, and told me once that he helped a lady pick a chair, while during that time she complained endlessly about the company. when someone helps a costumer purchase something, they put a sticker on the box to notify the boss, and that person get a small cut of the purchase, so when my friend put the sticker, she asked him what he was doing. after he said that it's to show who helped her, she said he didnt help her at all... my friend just laughed and tried to let it slide.
he told me that after that someone their said that she's a regular customer, and in the past one of the workers started arguing with her, so that makes the story even weirder...
point is, you're not alone in this shit, so your pain is being felt all over the world...