I don't know through what voodoo, but Google is showing images from by image folders that is blocked to its bot, following its own instructions!
Double-checking here: You mean within image search, not in preview?
Did you explicitly remove (de-index) the images? Image search, like ordinary search, doesn't check to see whether the image/page is available right now. It uses the information it's already got. Hotlinking by definition doesn't involve a detour to robots.txt, since there's no crawling. The user's browser is putting in its own request, saying "google sent me". Or, in this case, "I was told to ask for..."