This thread won't die!
For everybody who keeps referencing Mike Tyson and the famous ear biting incident - Tyson was the biter and Evander Holyfield was the victim of the bite.
I was wondering if someone was going to point that out.
Try not to go to the ground, good idea. But, if the ground swallows you up, because the other guy managed a good, slick takedown, or you stepped on a banana peel, whatever, you need to know what Not to do while down there. That list is relatively straightforward and simple to learn, probably takes 90 days of rolling with BJJ people to learn what Not to do, and it might be a good idea to know that.
But, to be honest, I very seriously doubt that there is a "Bad Guy" who happens to be a black-belt BJJ bad-ass out there a-hunting... I just don't see that happening.