We don't sell poisoned dog food.

Once the postman starts to publish a blog about his route will full name, address and a list of hair-loss products you buy, and rant about any farting sound heard while near your house, then you might have a problem. Each piece of data in itself is not a threat to your privacy as long as the owner acts within the boundaries implicitly or explicitly granted by you. When all this semi-public data is interlinked and published without consent or control your privacy is severely threatened. If I spend one hour in San Marco square I will become a part of hundreds of photos, and all those people should be free to upload the pictures and even tag me as "some random guy in San Marco square". When they tag me as "my real name, in San Marco square, on August 4 2011" I will have a huge issue with it.