First I rely in good part on HN proven ability to police bad behaviour. On top of that, by the very nature of the service and to extract good content, I will be focused on analysing the type of content posted. I will have a greater incentive to detect dishonnest, nefarious behavior.

I think light-astroturfing always happen, here less than elsewhereon the web, probably because it gets called out quickly by HN readers. And one of the key to having it under control is to bring it out in the open.