Reported by mrs aracer, not experienced directly by me (I'd have been a lot more rude). She'd left her bag round the other side of a pond the kids were sailing their toy boats on, when a dog came up and started sniffing/investigating the bag. She shouted at the dog to get away from the bag. Which resulted in the dog owner having a go at her, telling her that it was a public place and dogs were allowed to go wherever they liked and anyway it was only a puppy so what did you expect.
I think I'd have been tempted to get my phone out and ask if I should call the police to get their advice on whether dogs were supposed to be under control in a public place. But then I've had too many experiences of entitled dog owners.