> In addition to the comments of others, there could also be posts in the
> archives that are replies quoting his posts.  Should  they be deleted too?
>  How would the authors of those posts feel about them being deleted?

This is the main reason I do not delete posts. It is the nature of mailing lists that discussions tend to evolve as follows:

1. Joe says something stupid.
2. Jane and a few others flame Joe, quoting relevant parts of Joe's message (or nowadays, the whole message since Outlook makes it so difficult to quote with '>').
3. After a while, James quotes part of Jane's flame and a new, productive discussion starts off. In no time the original subject refers to a totally new, relevant and productive topic.

Sure you can delete what Joe said but it won't exonerate him from searches. If you edit Jane's message to remove Joe's musings, you will make her sound like someone who wrote a flame out of thin air, and she will be justifiably angry. Deleting Jane's message is perhaps even worse, and could make James sound like a clown.

What you could do, arguably, is edit the messages so that they say 'Anonymous' instead of Joe. Then the discussion sort of makes sense, not all the time but at least you aren't destroying everything.

Editing is treacherous in this age of multipart messages. You could end up editing only one message format and not the others. Best case, you'd have to do it twice.

  Eric