An interesting study in privacy awareness:
A context-aware approach to privacy is something that seems to have eluded companies like Facebook, Google, Flickr, Instagram, Snapchat and others. They promise secrecy and control, but what they really should be doing is making sure that people know what they can expect—to let them actually understand the ways in which your data might get shared.
I think for many people that's a big gap. It's not that someone will break into Flickr and steal your private photos. The problem is not understanding the permissions you grant.