Is it time to start calling out bad cyclists?

Yes, technically this is the correct use of the horn, all but a few uses are out of aggression in the real world. If your engine is so 'gruff sounding' why feel the need to make even more noise?

I toot riders on country roads who are about to do something daft. You can tell a mile off the newer / less experience/ less confident riders on the road, short sharp honk a decent distance away from them so that its not taken as aggression. Pretty much always get a wave as I pass.

Also having a bike on back or bike stickers on car helps reduce rider/ driver related un-needed anger, a bit like that jesus fish, but with wheels