You're responsible for keeping your dog under control to the extent that it's not a threat to innocent third parties. I don't care if you use a fence, a leash or telekinesis.

If you fail in your LEGAL DUTY to control your animal, and it puts me in reasonable fear of being bitten, it's probably getting shot. I don't carry pepper spray and don't intend to start. I have to carry enough stuff as it is. I'm not Batman and don't wear a utility belt.

It's YOUR dog and YOUR responsibility. I neither know nor CARE whether there are any "bad dogs". If your dog tries to bite me, it's a threat and prima facia evidence of your failure as a dog owner. That's on YOU not me. If your dog has to suffer as a result, I can live with that.