I remember watching as one kid said to another "I believe in you" to help out in some moment of crisis. It struck me as odd - something cheesy they'd (probably) heard in a movie or cartoon.

But if they are saying that to each other then I could probably use it to communicate better with them as long as it was sincere.

I'd say it sparingly when I thought it might be appropriate or helpful. The reactions were surprising to me, not at the time I said it, but later on. I'm not suggesting I was a major influence that sets kids on the right track, but I think it helped out somewhat and for some reason that specific phrase seemed much more powerful than other forms of encouragement.

The surface sentiment is enablement but there's always a component of "if you don't perform you're screwed" lurking in the background.

In general, I think a teacher classifying genius and dysfunction is putting people into boxes and may harm his students more than helping them.

I've never encountered a great teacher who talks like that. I've met many people justifying their existence and positions who do talk like that.

And the one who cant teach, complains about teachers.

In my experience people who say the above are unable to teach anybody anything.