Have you checked the data Facebook is holding about you? As a not very diligent user of social media, I finally got around to taking a look. Obviously it has a record of all of your posts, photos and videos & obviously it keeps all of the self-declared interests in music etc.
I was not surprised by the lack of contact information from my mobile phone or email because I can remember thinking “Not in a month of Sundays” when asked setting up the account. Some people have their entire address book stored plus a record of every phone call including the data saying where, when etc.
That’s a bit too spooky big brother for me!
I was freaked out enough by finding unexpected advertisers and installed applications.
All in all, I’ve managed to contain the data held on me to a reasonable level mainly by being paranoid at set-up and not much of a user thereafter.
But I would certainly advise anyone to take a look at the data held on them (via settings). If you’re not happy then delete (not disable) the account to remove the data and then set it up again with a bit more care about the settings.