It always scares me when I go to 'log in with twitter' and it tells me "$APP wants permission to ... update your feed." I always hit DENY and forget the servic

It always scares me when I go to 'log in with twitter' and it tells me "$APP wants permission to ... update your feed." I always hit DENY and forget the service if that happens. Maybe I'm being harsh, and the app doesn't actually want to tweet in my name, but twitter doesn't allow it to request read-only access. Still, the permissions as displayed are clearly not what I want to grant, and I don't get to veto only the update ability. I would rather not use a service than offer it the possibility of spamming in my name, and I have made that choice a few times now.