I wrote recently about Cassandra and how she appeared to be griefing my raid. It seems that everyone, self included, spoke too soon. I gave her a stern talking to and got her to sit at my side on passive on the early Bastion trash.....and we still got the adds. While it doesn't explain Magmaw, it does appear that Cassie isn't quite as vicious as I had thought she was. In fact, she really threw herself into destroying the trash with a vengeance to clear her name.
Grateful as I am that I didn't tame a prankster (or a second one, I should say; I still don't totally trust Odysseus), I was disappointed that I hadn't had more faith in Cassie or myself. It's very easy to toss blame on pets and their owners for bad pulls. Yes, sometimes it's true, but other times, it's not. I've seen a few hunters who don't even use pets in 5m instances because they've been yelled at for their pet's behavior before. They were fine when they did take their pet out too, which means they'd probably gotten yelled at for no good reason.
It bugs me to no end. I'm just glad that my immediate friends and fellow raiders aren't overly serious about blaming pets. I feel for those who are not so lucky.