I have not bothered to poke around and figure out exactly how viewership is being tracked. In general, it is easy to track when a page is loaded (an http GET request) but a bit harder to track how long a page is being viewed especially on an intermittent connection. I would guess that when a bot is loading and scanning hundreds of pages, nafex might not be tracking a page being closed and it might take a while for the 'view' to timeout. That would make it look like hundreds of guests are viewing when it may only be one or two bots actively scanning.
To investigate farther it might be interesting to look at more information about each 'guest' (see if most of them are from the same IP address, etc).