I think its important to
1) leave the closed topic on the board (as opposed to taking them down altogether)
2) delete the posts that were out of line
3)have us read the closed ones, so we see what brought them down.
Even with the deletions, you can often see where it was headed, and why the topic got shut. Last week, there was a thread about nail polish, and I kept out of it, becuase a month ago there was another nail polish thread where i did post (funny stuff IMHO, but the mods were not in a laughing mood :/ )
So hopefully, other people saw how my posts were out of bounds and did not make the same mistakes as I did.
Nothing wrong with learning from other peoples mistakes.