Well, I don't have a dog, but when I take my neighbour's dog, Bonnie, for walks, I always keep her on a leash. I would like to let her loose in a park, and she probably wouldn't do anything bad, but I'd be scared of losing her. If she was my dog, then I would, it's just that she's not as used to me as she is to her owners, and if she began to wander off she might not come back to me. I think it's great to see dogs having fun off leash in the park though