Just curious more than anything. Lately there has been a huge increase in the numbers of those "viewing" and in Who's Online....See attached files. The one showing viewing is an open forum accessible to the public. This may answer the query, but still seems odd and out of the ordinary....thoughts??
It's probably spiders; spiders that do not have a User Agent entered in the settings in the CP show up as "guests" just like non-logged in users.
To check simply look at the "Who's Online" page and hover over the "info" box (the box with an "i") and it should say "User Agent" which will give some information about the "browser" the "user" us on (in the case of Bot's it should show what organization they belong to).