The only problem with humans using "super-smooth" shoes to walk up walls is a matter of surface area/mass ratios. It's a similar problem to the one of why humans can't walk on water even though water striders
can do it. A water strider's mass is so low relative to its foot size that the pressure of the foot is insufficient to overcome surface tension; to dupilcate the effect, a person's foot would have to be about 5 square kilometers large. A gecko's feet, compared with the rest of its body, are huge -- each toe is about the relative size of a human's whole foot. So in order to make this work for humans, you'd have to use a whole lot larger area than just the foot, or drastically increase the size of one's foot.
It's still an interesting node about geckoes, though.