Is it time to start calling out bad cyclists?

I really wanted to but I didn't want to come over as being condescending, should have suggested cycle training but that often brushes people up the wrong way.. What does one say in these situations? (serious question)

Telling some to get some cycle training will usually get a frosty reception. But to suggest riding down the side of any vehicle where you can't see the driver seeing you is a recipe for trouble or even something about a fatality on that exact stretch of road could bring it home.