Dog parks are the best place to take your dog to see if your dog has any aggression issues with other dogs. Just think there are a bunch of dogs running around and YOUR dog knows you are in the fenced in area and may be in danger of other dogs, so just maybe they think they need to protect you. A responsible dog owner will keep an eye on their dog in the park to see if any aggression is about to start with any dog. This is not a pace for people to stand and chat with each other and let their dogs bully others until there is that dog fight.

Nothing wrong with a clean well run dog park.