Most "guests" are spammer bots and the like. For instance, looking just now there are a dozen "guests" on from the 54.36.xxx.xxx domains all from France. Also some Chinese (in an old Ebola thread, interestingly).
We have the forum set at this time to require new account approval and we have anywhere 50-100 "people" signing up every day that have to be checked and deleted. Almost all of their IPs resolve to places like Ragistan, commie pinko countries, etc.
Also, not sure what they're doing in "report a post". They're not reporting posts. I think the last reported post was at least a few weeks ago, by an actual member.