The funny thing about that is there sometimes are flaws in the sprites of TSR; the rippers are not perfect. Perhaps this is something that I would only notice, but if someone changes the background color, they are probably going to be amateur about it and places where the sprite contains the original background color will not get changed. Moving images around, if not done precisely, can be perceived by the viewer due to the layout of the sheet. They will probably leave sections of similar sprites a certain way, so it would be easy to compare using that. In my opinion, trying to pass something off as your own like that would be too much work.