I worked retail a couple times, just for the Christmas season, many years apart. Hated it with a passion both times.
pointed out, I was required to look at the credit card and address the customer by name. Knowing that I found it annoying as a customer, I disliked doing it as the salesperson. Even worse was having to ask anyone who paid with something other than the store's own credit card whether they wanted to open an account. Of course they didn't.
I treat cashiers the way I want them to treat me: I'm polite, I'm pleasant, I'm usually not all that friendly.
My worst encounter:
Last winter, when I was still using a cane and had an infusion pump slung over my shoulder, I decided to try on a cape. The saleswoman heard me tell my friend that I usually don't like loose, floppy clothes, but sleeves were uncomfortable over my PICC line, so a cape would be perfect for a while. So she starts telling me how great I look for someone who's sick, and how many capes she's sold to women who use wheelchairs, and btw what was wrong with me anyway.