Yep, sounds familiar, although our dog is hard to train. At one point, when he was just a puppy, we tried him to teach to lie down. We overtrained though, and for months after that, he assumed that everytime he got his food, a cookie or we were just looking at him, he just crashed down, really, it was just crashing down, he just plunged to the floor. He still does that sometimes, when we want to give him a cookie, we say "sit" but instead of that he lies down - it's of course not as a big deal as your experiences, but the idea is the same
By the way, we thought of taking a Cocker Spaniel, especially my mom is fond of them, but then we saw a Beaglepup and we were sold ... hahahahaha.