I had a very public, loud argument with another dog owner two weeks ago about keeping dogs on-lead.
We have two dogs - both rescue; one is an older, large mutt, after lots of work she's very friendly with every friendly dog we meet, but has a degenerative muscle condition that means we keep her on lead at almost all times to try and protect her from doing anything silly; the other, medium-sized mutt, we've had for a year, and we're still working on his confidence, he's muzzled and on-lead for his own protection when in situations where he might meet other dogs with no 'escape route', eg. narrow footpaths.
Anyway, an off-lead collie was stalking us as we walked through the park, then ran at us, hackles raised, and began circling and barking. Owner, with headphones on, just kept walking and did nothing. Our two got agitated and barked and lunged back. Collie eventually gave up.
OH walked our two away, whilst I said to the owner that he needed to control his dog. He said - as ALL such owners do! - that his dog was the friendliest dog in the world, and just wanted attention. I said that his dog was not under control as it ran at our dogs and he didn't intervene. He said our dogs must have been the problem for being on-lead, and asked why they were on lead anyway. It went on like this for a few minutes! Other people tried to avoid looking as they walked past! I gave up trying to reason with the guy and just reiterated that all he should have done was have said sorry because his dog was not under control. Trying to have the last word as I walked away, he called out that that was my opinion but I was wrong. During this raised-voice discussion, the collie got between us and started fixing on me. Not at all friendly, and quite unnerving, especially with an ignorant owner who can't tell the difference between friendly signals and non-friendly signals.
OH was upset at me for making a scene. I explained to OH that I was upset because we were working hard to build our newer dog's confidence only for idiots like the other guy and his dog to undermine our efforts. OH then quite rightly pointed out that irresponsible owners can't be reasoned with and that, whilst I was upset for hours afterwards, the other owner likely hadn't given it a second thought.
So, my point is, as a responsible owner of a dog that others perceive as dangerous, your job is to be an ambassador for the breed - muzzled, on-lead at all times, regardless of proximity to others, so that you always know that you've done your best and there's never ever going to be any opportunity for a mishap. Ignore the ignorant and be beyond reproach.