Is it time to start calling out bad cyclists?

Headphoned chap on a pink SS this morning riding slower than a lot of cyclists, but then aggressively undertaking the lot of them when the traffic slowed down, repeatedly. And doing little tailwhip-y skids using the rear brake. Silly boy.

undertaking people that you're not riding with is rarely ok. and you should at least say something before you do, like 'coming up the left' or 'on your inside' or something. i wouldn't expect people to check their left shoulder before moving in to the kurb if they were in the left hand lane already