The worst customers are the ones who are broke.

Example 1: Returning without a receipt something that was obviously from 2015.

Example 2: Expecting returns on credit card purchases to appear on their account instantly. This is my pet peeve. They return something. Good. Then they try to buy something and the card gets declined because it's maxed out. Then I'm blamed for their bad financial decisions.

Example 3: Returning something that's been washed and bleached? Sorry, dude. I'm not Nordstrom. If you wanna do that shit, you'll have to build some goodwill and relationships with the high-end stores.

Example 4: I can't reiterate Ex2 enough. Money doesn't show up at your account instantly!!! It's not my fault your cards are maxed out.