Is it time to start calling out bad cyclists?

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.

They do appreciated a good CockPunch™ though.