Is it time to start calling out bad cyclists?

Etiquette Question:

What do you do if you come up to the ASL and the cyclists already there look as though they'll be pretty slow?

I usually neatly file behind as I think it's a bit rude to just push past. But the other day it seemed as though every light had a dutch town bike.

Am I right, or just being over sensitive?

Yes, sit behind, overtake later. You can never tell how fast someone is from how they look.

I look slow whilst stationary on my shopping bike, but am actually awesome. When folk move up to sit outside me at the lights thinking they're quick I very much enjoy moving off at the same rate as them then keeping exactly the same pace on their inside until they give up and tuck in behind.

It's a great game.