I have worked in customer service for ... ever. The customer is always right (mostly). I work for a pest control company and people can be really, well lets say not smart. As much as I would love to say "listen lady can't you read? You signed the paperwork and initialed the instructions that were printed in bold letters across half the page" instead I play nice and try to defuse the situation. I think as a seller with a customer basis whether it be eBay, amazon, or yard sales its always good not to insult your customer.
A few weeks ago I went to a yard sale and the seller looks at me and says "I don't have any clothes that will fit you." I could understand if she was a size 2 but she wasn't small. I looked at my mom and she snickered and whispered "she's calling you fat". Not nice! I just smiled and continued looking at her clothing.
It's hard to remember sometimes but customer service doesn't stop when you leave work. As an eBay buyer recently I started thinking about my customer service skills as a seller. I had some great sellers who responded right away and were so nice and helpful and some not so nice sellers. I only do eBay part time but it is still my "business" and I have to carry my "customer is always right" attitude home with me.
And I think as a general rule we should always remember to treat people the way we would like to be treated. So that is my new goal as a seller. Have the best customer service ever!