It is a fairly slow ride, but they are know for intentionally block car traffic (on 4-lane one way roads), blocking pedestrians, unnecessary corking, starting yelling matches with drivers, and other not-so positive behaviors.
(It wasn’t always like that though.)
The way CM started to act in Pittsburgh is the biggest reason Flock was started.
Corking is blocking the cross traffic from moving with bicycles strategically stopped in front of cars. They do it on CM rides when they run red lights and want to stop the cars with green lights from moving into a gap in the bicycles.
I cork sometimes on flock rides too, like when we pull out from Panther Hollow Bridge onto Blvd of the Allies. It is always clear when we pull out, but a bike sideways in the road lets the motorists know they should probably just change lanes, instead of inserting themselves into our group.
Corking for running red lights when you have 13 people with 3 bike-lengths between each one is stupid.