What's appropriate on Flickr?

Nasty as they wanna be? Policing Flickr.com

What kind of photos are appropriate on Flickr?  What kind of photos are inappropriate when your rules include:  “No Commerce.”  “Don't be creepy. You know the guy. Don't be that guy.” and "Don't forget the children."

This is an article from the San Francisco Gate about the people that police the world’s most popular photography site.