Facebook – Are Photo Tags Automatically Removed When Blocking Someone?

I don't know for certain (I don't work for Facebook!), but from my experience it seems to bring back results in (approximately) the following order:

1. From your friends
2. From your friends friends
3. People with common interests (liked pages, shared groups etc.)

After this it starts to become more guesswork, but I suspect that home town, shared work places etc all come into play as well.

With more than 500 million users there's a lot of data and existing connections they can use to base their heuristics on

Good question. Let me explain the answer one by one.

1. If you are the one uploading that photo, your privacy settings will apply to the post. If you've set the friends of friends settings, all the friends of your friends can see the photo, if you tag your friends in it. The exception is if you've explicitly excluded a person or list from the post. In that case they won't be able to see it, except if your friends reshare the photo.

2. If your friends is the one who uploaded the picture, his/her privacy settings will apply. The person you've blocked can see the photo, but can't see your tag in it.

3. Same as answer 1. He can't see unless the post is shared by one of your friends.