Yes, the metal side had to be a smooth expanse of metal...it seems the person working on the fly-in coop even warned against screw heads sticking out that the coons could hang a toenail in...In order for sheet metal to be effective you will need to have is as a sheer wall. They will bear hug their way like human child or monkey will otherwise. The electric netting would be a quick approach although you could make so a single strand of hotwire would have similar effect with that coop.
Greasing a pole/post or whatever... Purple martin landlords have tried greasing the poles to their gourd racks to prevent snakes from climbing the pole....they usually end up with a greasy snake in a gourd. I would imagine a raccoon would do about the same. Some type of a flimsy, smooth baffle mounted to extend out from the bottom of the coop several inches (8-16"..???) might prevent a coon from attaining a handhold to pull itself up with....but then the baffle would probably be in the way of the chicken owner in working the coop and sharp edges injure the birds. The baffle might work just mounted to the legs. Envision a large, flimsy plate with a hole in it slipped up a coop leg and secured just beneath the coop box...a raccoon climbing up would have to reach around the plate to grab sure footing, if it gripped the edge of the plate the plate would bend under the coon's weight...it would have to be clean edged so no chance of a handhold would be there. Just thinking...
Ed