By logging into a 3rd-party site using Google+, for instance, you remain logged-in to Google when you go to any other web site. And the authenticator clearly d

By logging into a 3rd-party site using Google+, for instance, you remain logged-in to Google when you go to any other web site. And the authenticator clearly does not require this global behavior: if you immediately log out from a Google page, you remain “logged in” at the 3rd-party site that you started from. So why doesn’t it log you out globally? Probably to convenience Google, at the expense of security when you auto-identify yourself to who knows how many other web sites before you realize what happened. Logging into one page with one set of permissions should mean “LOG INTO THIS PAGE”, not “REVEAL MY SECRETS TO THE INTERNET”.