I vote for simply deleting the whole thread. Seeing replies without the original post is going to be confusing. Yes, there may have been some good replies, but on the whole, bad nodes are not going to get good replies. Most of the really "bad" ones are either personal attacks or just someone fooling around (like cutting and pasting code from other nodes, or posting purposefully bad code). Maybe an exception could be made for replies that actually have really, really good content, but as a rule I would say to delete them.