And one thing they might want to do next is check that privacy policy and user agreement.

That's the minimum you should do as it at least allows you to know what they're taking from you, if you can penetrate the language.

But because these Terms of Service, User Agreement, Privacy Policy, etc. are non-negotiable, it's pretty much an all or nothing situation. You cannot choose how much of your privacy is eroded, just whether or not to volunteer at all.