I worked in retail too before. You're going to meet every type of person, and a lot of them aren't pleasant. It's in the best interest of everybody to simply complete the transaction as quickly and smoothly as possible. I don't want to see their ugly mugs nor do they want to spend time with me. If I let every customer like this get under my skin, I would gone insane long ago. The people in retail who actually do spend the time messing with customers usually just end up provoking them, which leads to the crazier ones to flip out and cause problems for everybody else.