The original paper asked if images that could fool DBN.a could fool DBN.b. The answer was: certainly not all the time. They used the exact same train set and architecture for DBN.a and DBN.b, just randomly varied initial weights. I think this is too favorable for a comparison with a voting ensemble made with nets with a different architecture, train set and tuning. Can they also find images that can fool DBN.a-z?
Also, to test if a net can learn to recognize these fooling images, they simply add them to the train sets. Those noisy images would be far simpler to detect: They have a much greater complexity than natural images. To detect the artsy images, a quick knearest-neighbors run should show that they do not look much like anything it has seen before, so it may be an adversarial image.