"Oh thats a nice car they have!" You may think while staring at a strangers house. You may not realize it, but that is pretty creepy. How would you react when you see a complete stranger walking by your house and they just stop and just stay there and stare. Would you feel a little creeped out; and wanna call the cops?
Now I'm not saying Google earth is a bad idea, it's just how creepy you can be on it. So just try when you're looking at some olds friends house, try not to look at strangers houses. It's just plane creepy.