The nice thing about indexing the whole web is that you also have a complete per-author picture of everything they've written. Shills often post the exact same message on many different sites, or talk exclusively about one project and nothing else. Gamblers & laymen tend to pop up abruptly when a project gets hot, and then quickly either disappear or move on to the next hot thing. When a veteran user with a reputation for detailed, often-quoted posts starts talking about a particular project, though, and keeps talking about it, usually there's something real there.