Yes i have been scammed before, 2 times the first was from a guy over at yaxay and wanted a phpbb skin, so after the guy gets his skin i ask him to pay and he did a runner!

The 2nd time was when i wanted a flash banner made for nexuslabs i posted details about it over at sitepoint and i hired a guy called TheHazelOp to do it, and the fool ripped a banner made by banners2go, i reported him as you already know

From now on i tell all my clients i want at least 20% payment upfront before i even start.