Quote Originally Posted by Poulp' View Post
Let me use a concrete example: a poster posted a message advocating piracy.
Do you moderators:

a/ wipe the post out of existence.

b/ delete the harmful parts. Warn the offender, publicly, in his post, and through a PM, but leave his post where it was - most probably with a line or two of **********.
TC's explained the principles. On your specific example, I think most moderators here would do (b). Typically warnings are private, not public. But when someone advocates piracy, it's common for the moderator to say something in the thread, to stop the flood gates opening.