I did a life-event sketchbook for a wedding, wherein I capture a variety of the moments in quick, often humorous, illustrations.
Despite being clear on my pay beforehand, the client had second thoughts on my salary after the event. I told them to look through the sketchbook to clarify that it was solid work before they paid me.
They kept the book for over three weeks before sending it back, stating that it was too expensive for the quality.
Within a week, I saw scans of all my sketches released via their Facebook account.