For whats it worth, this is my impression of a bull shark dive I did in Playa last Nov.
I did not plan to do a bull shark dive. I was booked with a small dive op for a regular ol dive. But they had another guy who came over specifically from Cozumel to do the bull shark dive, so I went with it.
At first, I admit it was exhilarating -- they swam around at arms length. However, after awhile, the bull sharks just seemed to be waiting around, swimming without purpose. And the dive consisted of us stuck on the featureless bottom, watching the sharks. At the end of the dive the DM fed them.
So, I feel like I wasn't seeing typical wildlife behavior. They actually reminded me of my dogs when they want a treat. My girls walk around and around the cabinet where we keep the treats until they get one.
In retrospect, I don't agree with chumming and will take care to avoid it in the future.
On another dive, I caught sight of a baby bull shark in the distance. I remember this more fondly, bc I feel I actually saw a shark doing what a shark does in the wild. The bull shark dive I did was a bit like watching trained circus animals.