what is everyone's definition of a cattle boat?
Mine would be "a boat on which divers are treated like cattle". It can be large or small, but larger boats lend themselves more to this practice.
I was actually considering a trip to Cozumel with my son... Doesn't sound like the place to dive anymore. I dove there 25-30 years ago.. I was not like that.
As others have pointed out, it's not like that now unless you end up with the wrong shop. There are many good shops, each with its ardent proponents. (I'm actually not an ardent proponent of the shop with which I dive, but that's a long story that's not for this thread.)
I'm just back from a week on the island during which we did no diving. We did, however, meet up several times with our divemaster friend and plan our next dive trip. We also spent a day snorkeling at Punta Sur, which my wife has done several times but I've managed never to have done before.
Cozumel is still plenty of fun to dive.