@HackToHell Sure, if you aren't doing much with it, then it's usually OK. But since guests really aren't very isolated from each other, one misbehaving customer screws it up for everybody.
@MatthewWong @Bob you're both more than welcome to test this out... If I see you steal my code though... I'm going to hunt you down and the last image you see while living will be something like this: sstatic.net/stackapps/img/404-connery-zardoz.jpg
(actually least for most of the sites, it seems worth hanging out in chat, just to get a feel of the dark steamy underbelly of it culture of the site as a whole)