Okay, I know the discussion has moved on well past this point, but:
It's a bit like typing celebrities - you're using a very narrow view in order to try and work out what the whole picture looks like. A narrow view that they've chosen to display to the world.
And (like in writing: every piece of writing is subjective, even the most analytical), when someone makes a choice to show or not show something about themselves, then their 'personality', as it comes across to us, is altered somewhat from the truth.
If you want to call that deception, then I suppose yes, everyone is being deceptive. They have no choice.
Anyway, even if someone is very honest and open on these forums, it is still very difficult to truly determine their true type from that alone. If someone, like whatever, is deliberately exaggerating or filtering various parts of their personalities, then typing someone accurately would be next to impossible. You might have your suspicions, but nobody but the person themselves could really say for certain.