Used correctly, a choke collar should never actually choke a dog. Tasha's class recommended it but I don't remember it actually requiring it. The teacher spent careful time demonstrating how it should be worn and used, so that it just causes more like a nudge to get the dog's attention, but NEVER choke the dog.

Used incorrectly, it can be a bad tool. Used correctly, it is not in the least cruel or unpleasant.