For some reason, it seems like this guy has nothing better to do except go around and try to tell people about how horrible their dog is. It’s a bad way to pick up women, who don’t want to have anything to do with him. Not only that, but it’s obvious he doesn’t know anything about dogs because if he did, he wouldn’t assume this woman’s dog is a horrible pet.
She told him who’s boss by calmly explaining how well trained her dog is, and that he doesn’t chew up any toys. Maybe his tactics worked with someone else, but they certainly didn’t work with her (via Constative).