I really think deleting posts just doesn't work. maybe highlighting them so people know that MNHQ consider the post inappropriate, but with deletions it can be impossible to know what on earth a thread is about, and so the deletions derail it, or spawn a flurry of pms. I think it would be so much better to just let everyone make their own minds up,but to be aware of MNHQ ruling on them.
In a sense this also applies to deleting threads. If there is a bunfight on a thread, I would like the chance to go back in a calmer frame of mind, and see what really happened, evaluate my own contributions, and even apologise if I feel I need to.
Another problem with deletions is when posts and posters are subject to abuse about bunfights that are no longer visible. I know the thread about a thread should in theory sort that out, but we all know it is a tool to use lightly. I really the feel the fundamental 'unspoken rule' that you leave a fight on a thread. You should be able to disagree on one thread, and agree heartily on another. There is a worrying emergence of a culture of grudge bearing that I feel is not in the spirit of the site.
And as a last point of the general deletion thing, I think on extremely contentious threads, of which there are relatively few and far between, I do believe that hard cases make bad law. But here I believe MNHQ have to be really proactive in laying their cards on the table about what they consider appropriate or not. It would save a lot of fighting and name calling.
And if posters want to hound other posters off threads and MN itself they need to dealt with very firmly.