I guess it's just a little odd how the HN moderators are quick defending millionaire VC Marc Andreessen, but have had nothing to say when others have been accused of astroturfing. In the other cases, it's been enough to let the voting system do its work, but in this particular case, the mods are quick to point out the weaknesses of the voting system and accuse nay sayers of lacking civility.
It's true that we don't catch everything; we don't see everything. If you or anyone would like to help, we'd be grateful. Gently reminding users not to break the guidelines is one way. Emailing us (hn@ycombinator.com) when you see them being broken is another.