2. Facebook has acknowledged (multiple times, now) giving read/write access as long as you were logged in through Facebook to one of these systems - you don't have to explicitly enable it and engage the message service, which is what OP was saying.
3. They say: "No third party was reading your private messages, or writing messages to your friends without your permission." They aren't saying that no third party was reading or writing messages, just that you gave it permission to do so. Unfortunately, that permission was, again, not explicitly given. It was a blanket (access data) permission. Facebook has a documented and admitted history of obfuscating what permissions you are actually giving it - the messaging app being one example.
> even if you don't use the service, CuteApp can still access your messages. You don't actually know about the service
I don't disagree that permissions dialogs can be confusing and misleading, but you were initially claiming that CuteApp could access your messages even if you have never used it. Are you no longer making this claim?
If they truly knew half of what these applications were doing with their "private" information, I can guarantee less than half would continue using it.