I don't use any Facebook apps so I can't attest for their accuracy. If you are concerned about privacy make sure to read every single word in the T&Cs or any app you approve or quiz you take. Most will state that they will use all of your and your friends information and Facebook allows this in their SDK. I have no real problem with this because it isn't like it is a secret and I really don't care who views my page or sees the info I post there. I won't put anything on there that I wouldn't want anyone to see. I will only put something up there that I wouldn't mind my boss, any potential employer, or my future children to see. Using that as my barometer just seems the best and most logical way to go.