With a few exceptions...there really is no such thing as a bad dog...just bad dog owners. Unfortunately some people think their dog is special and shouldn't be subject to the same rules as "other dogs". I see it all the time in campgrounds (for that matter any public space), where dogs are allowed to defecate anywhere and owners never cleanup, or the dog is allowed to bark and howl all the time. I have been in the city park and watched dog owners let their dogs chase the ducks and geese around as though that is good sport. Yet if you try to have a conversation with these people about their dog and the rules, you are simply met with anger. After all, their little "fur baby" is special.
I have never seen (or heard) of any dog owner being penalized for the bad behavior of their dog...unless it mauls or kills someone, or kills someone else's pet. Maybe some stricter enforcement and fines for the owners might curtail some of the bad behavior of their pets. But that is just a pipe dream. So, unfortunately, when being attacked by a random dog, with no owner in sight, one is left with little defense except to do whatever is necessary, with whatever tools are at hand, to preserve one's own safety.