lucy24 - 12:21 pm on Jan 16, 2013 (gmt 0)
That is apparently enough for Google to think the image belongs to this site?!?
I don't see how you get from A to B. Did you give your site name as a search term or in a "site:." construction? If all you did was search for images involving your sitename, then links to images on your site would be a natural result.
Anyway the joke is on the offending sites because your hotlink routine does prevent their users from seeing your images out of context. At least unless they're savvy enough to right-click, copy the link, and then paste it into their browser's address bar. (I hope the site does not explicitly instruct them to do so, because that would be Evil.) Anyone who tried clicking directly would slam right into the same "Stop Thief!" graphic that your hotlinkers see.