I've job changed to tank from a non tank job for something like expert roulette and ran through grabbing the first large pull before noticing I forgot to turn on tank stance.

I think its more disturbing I've done this on occasions and not noticed tank stance was off until the pull was dead because I wasn't actually loosing enmity to DPS. Makes me think they aren't doing their job since my name isn't Maple and I haven't sunk all my stats into defense to the point I'm immune to any damage a boss deals and can kill it by eating it... >.>