I think everyone agrees that they tend to act differently if they know they are being watched. For instance, would you masterbate if you thought someone was watching you through a camera? It's not a crime to jerk off (at least in most places) yet most people would have a big problem with some stranger watching them do it. Likewise, would you visit an anti-government site if you thought that some FBI agent was logging your activity? If you were a girl and were worried that you were pregnant, would you feel comfortable looking up
pregnancy information at the public library with librarians watching over your shoulder?
Anyway, there are some things people don't see as "wrong" like ordering sex toys online, etc. -- but you wouldn't necessarily want your boss or some random person knowing about it.