That last story reminds me of when I worked in a b&b in a tourist town. Two German tourists came and I gave them a map and directions to the Cliff Walk. They came back with armfulls of a lovely, shiny leaved green vine that they intended to use to make wreaths. I looked at the plants and told them I thought they were poison ivy. Sure enough, next day they were both covered in raw, pink welts. D'OH!