The problem with the stars is that as long as they get NO feedback, it's like getting positive feedback. You'll notice your rating climbs with every match you play online, whether you get positive feedback or not.
So basically, whenever anyone's being a dick online, be sure to give them negative feedback (set them on avoid and say why). Otherwise, it's like you're telling everyone this dude's OK to play with.
One more thing -- check their gamercards when you're about to play. If you check their rep, there are actually records of how much bad feedback they've got and what it was for (percentages pointing out feedback for cursing, causing a commotion on voice chat, disconnects, unsportsmanlike, aggressiveness and so on). Don't just rely on the star rating, but dig a bit deeper and see what kind of gamer that person really is.
Personally, I think they need to change the rep setup a bit. Having to give specific feedback for an "avoid" is a great idea, as is recording it. But equating no feedback to positive feedback is stupid, because you have to figure 85% of the folks you play against won't leave any feedback at all anyway.
