Found this official ACS demo http://www.fabrikamshipping.com/ while researching on ACS.
In the app itself, when logging in with one of the providers ( I chose Google ), I can see in the browser history the URL that contains the claims returned from ACS. It's the URL that starts with :
Going to this URL logs me in the app, even after clearing all browser cache and cookies.
So if I log in to the app from some public computer, and then log out, my account is exposed by going to this URL in the browser history.
I know this is the standart way that ACS Identity handling works.
What am I missing here ?