I was looking for a Fiery Beholder Eye which sells/sold for ~2000g on my server, but no-one seemed to even have one so I was about to give up. I logged on a couple days later and one was sitting in my mailbox for free from someone who said that I'd been the only nice person in trade to them and they'd never forgotten it.
That still makes me smile, but also makes me sad that someone had had such a horrid time after just asking a question that the one nice person stuck in their mind. Answering questions is hard, right?