I think it would just end up with trolls pasting in Lorem Ipsum or something after their trollish comment. Having trash text in low quality comments might make them easier to identify as low quality and the need to post comments of a minimum length may possibly discourage some people from posting "zingers", but I don't feel it would be a net win overall.
I don't think so. I think the vast majority of users will down-vote and/or flag comments intentionally padded with nonsense.
I'd like to see a more sophisticated quality detection system - a learning text classifier of some sort. PG might have enough experience in that field of programming to come up with something useful along those lines.
