This happened in one of my puppy obedience classes with my eldest Lab (now 7). In my case, it was a woman with an ACD. Now, her dog was NOT soft at all. ACDs are well known to be independent thinkers and some can be bull-headed. She basically starting swinging her pup in a circle by the lead (all four feet off the ground, so imagine someone winding up to throw shotput or discus). The teacher hadn't arrived at class yet, so it was just a bunch of students hanging around. I didn't raise my voice, but just said, "Hey, maybe try doing xxx instead...I worry that your girl is going to get hurt." The owner didn't really react, but she didn't swing her puppy in class again. My guess is maybe she trains that way in private, but at least in class it was toned down.