I remember working on integrating facebook with an app I was working on several years ago. It was in the pre-M days, so Android was still using the old install time permission system.

As soon as facebook would be installed without even running the app, it would access the contact database and do network operations (very probably uploads .. ).

For this reasons, well among many others, I never installed the facebook app on one of my personal devices at the time.

In their credit, when M arrived, they have updated their app pretty quickly to the new permission model.

Still, I try to be as conservative as possible with critical permissions.

The only one I regret is whatsapp now that facebook owns them.