the one last night that was clearly un-escapable
But miracles do happen and there is a way out of everything, the problem is the debates it would cause. "it looked locked in ref but I was just about to escape, I had it under control"
There's no definitive way of judging it, like you can judge if someone is asleep or not, so it should be up to the fighters. They are pros after all, they know the risks.
I reckon there could be rules on it though. If a fighter is generally a submission artist and breaks a limb on someone, he should get a warning that if he breaks something again, his motives and technique will be reviewed. There is a middle ground between breaking someone's limb and not holding the submission tight enough to be effective.
E.G if when you get an armbar and they are quite defencless, if you yank it back as hard and fast as you can, you could say you were trying to do damage, which shouldn't be allowed. Then again that creates a grey area in that fast grappling results in fast submissions.
All in all I think if one fighter has a reputation for doing it to people, he should be questioned about it. Otherwise, it's just the nature of the sport.