Probably what goes through your mind whenever you see someone posting some traced, copied, deadleaves, jetgrindradio, paprika lookin stuff in the art forum, and you cant really prove it. Well try your luck with this
Its a reverse image search engine, that actually looks for copies or likenesses of an image.
I don't know how many of you already know about it, so disregard if you do, but they seem to state its pretty new which is why the search isn't really 100%, but the more you search with it, the bigger its library gets so we should all use it often.
This is also a cool way to track your art. Just to see how far it has spread and where things end up may yield interesting results. So I say it doesn't hurt to play around with it.
The only downside is you have to register to use it. I'm assuming to prevent it from being spammed by bots.
either way, doesn't hurt to mess around with it.