It is often smart dogs that are hard to train. You just can't make mistakes with them, they learn so fast. Before you realize it, you have accidentally taught them something you didn't mean to, or that you regret teaching them, and of course they can't easily un-learn it! A friend of mine thought it was cute to teach his Golden to put his paws up on the counter. Haha very funny. Until he set his sandwich down, turned around to get a glass of milk, turned back around to find the sandwich gone and the dog licking his lips! Wohah, who's laughing now?