Besides saying 'hello' and 'thanks for the group', I tend not to talk in pugs. I will speak up if someone needs something explained to them, but I personally don't see the point in talking more than that if I'm never going to see the people again. :O I will use auto-translate if I see others using it, as a courtesy on the off-chance that they do not speak English as their first language or they simply aren't comfortable with it. The majority of players I have met are comfortable speaking English, though.

You're right that using auto-translate will lessen the chances of someone insulting or trolling you, but only because they know they can't affect you if you don't understand them. If I don't react to their internet 'bullying', they also get no satisfaction. There was once a dude in a Castrum run back when people did that for philo... he was a 2nd tank and refused to do anything... MPK'd us multiple times, but we couldn't kick him because votekick didn't exist yet. He just laughed and told us to carry him. We all mass-reported him and then just ignored him and moved on. I'm not sure if anything was done about him, but the fact that he didn't get any of us to rage or freak out probably disappointed him.