When I use a Facebook account to login to another website, what does 'logging in with Facebook' allow that website do with my Facebook account?
Can they post messages on my wall or news feed or anything else that might be considered unwanted, especially if it is without permission?
Edit: after having another look around, I found an authentication message for another app that said "... may post status messages, notes, photos and videos to my Wall" - can apps do this without separate permission before the post is made?
Can apps ever push any kind of messages to my friends (and can they do this without asking at any point)?
Is there any way for others to tell what services I use Facebook to login with by looking at my profile?
How can I tell if a website that I create an account with through Facebook will post my full name on their site?
I assume that all of this would differ based on different implementations, but would I always be able to tell what I am getting myself into by looking at the 'Request for permissions' page?