Is it time to start calling out bad cyclists?

It's extremely hard to intervene in a way that other road users can respond positively. Calling out, the question at the heart of this thread, seems to entrench rather than enlighten.

There are at least two types of bad cyclist: those that are bad because they're nervous/unsure/poorly trained, who in my experience seem to appreciate polite advice (at least to my face!), and those who are bad cyclists simply because they're dickheads. The latter type don't seem to appreciate any kind of talk, unsurprisingly.

Pretty much these. Though I'd opt for a screaming match if it diverted someone's attention from meeting their maker in front of my eyes.