Google, Yahoo ect bots aren't exactly smart enough to know that when you follow the "print" link, you're going to see the same thing. Those "print" pages are archived just like everything else and while the bot is on that page, the Active Users will say that GoogleBot is printing.
Likewise, if the bot follows a PM link, the record will show that they're "using the messenger."
As for guests posting, perhaps they're trying to do so unsuccessfully.