I have only ever removed 1 post, and that was only because it was a blatant ad for the person in question that added nothing extra to the discussion. If the comment had started off constructively it would have stayed!

All of my comments go up automatically. To be fair, there is a third way - which is actually a selectable option in WordPress - which is that the first post by a new commentator is moderated but all future comments are approved by default.

People tend not to understand how massive spam is. I have had 1,100 spam comments at Head for Points in the last 24 hours, of which Akismet (the spam software) let through a grand total of 1, with 0 false positives.