Bots are excluded (the browser user agent has to contain one of a number of fixed strings), the question author is excluded (apart from the first view), and sequential requests from the same IP address are excluded. But views from the same IP address are counted if a different IP address views the question inbetween. This does leave open a window for determined abusers, but on the other hand, I don't think it makes sense to add a database row for every view on a questoin.