Is it time to start calling out bad cyclists?

You seem to be missing the point. The vast majority of people that ride a bike consider themselves to be a good cyclist. However, that's not really relevant at all.
What is relevant though, is that it makes sense, does it not (please respond properly instead of resorting to silly name-calling and stereotyping), that when one cyclist sees another making a mistake, or riding dangerously, or generally causing a nuisance on the road, they should give some friendly advice?

Now, whether the recipient of that advice takes it to heart or not is up to them. The idea is about raising awareness within the cycling community of issues and dangers which do arise, and trying to prevent them from causing anyone harm.

No, it's too arrogant. Unless they are actually endangering you then I don't think you really have that right to make that on the spot judgement. If they wish to do something that you deem dangerous, let them, it is their life to live. Do you go round stopping smokers in the street and giving them advice?