I met a very interesting marauder yesterday, in EC through groupfinder. At boss fights, he actually seemed to know what he was doing: he run away from aoes, attacked the right boss and seemed to be familiar with the mechanics. But with thrash...it looked like it would be his first time. He kept running ahead of everyone, aggroing stuff he shouldn't aggro and once even attacked a target when we stealthers tried to cc the closest ones so the group could skip the mob. And you can guess twice who this guy attacked. That's right, a cced one!
It was pretty funny, since we actually never wiped even though he aggroed something. It was like he would have watched boss fight videos and read tactics until he could do the bosses in his sleep, and then he was in such a hurry to get to those bosses that he forgot that there are mobs in the area, too.
Maybe he felt like there's no need for any tactics on trash. I wouldn't be so bold to do that in ops, but in FPs, when I know it will make zero difference, I'll pull before tank without thinking twice.