Put a witness mark on ours after the first time and never had that problem again.

Yeah, "race to the bottom" really nails it. I did the same thing with a freelance editing job, spent like 3 hours on a sample rewrite, and they used it as a template for their whole website but hired someone else. The worst part is I saw them repost the same job listing a week later asking for more free samples from other people. It just made me feel stupid for letting them use me like that, and mad at myself for not trusting the people who warned me.

@angela728 reminded me of a client who once paid me extra to work Christmas then acted surprised I wanted the same rate for regular weekends.