He might not be the best singer or best song writer but he knows how to entertain and conenct with his audience.
I never thought for one second he was smashed off his face on drugs during X-Factor. He's publicly said he was addicted to prescription drugs, and he struggled for years to get off anti-depressants which he was prescribed for his anxiety and depression. Now, he's totally off them all I'd say he's having to deal with everything as he was used to hiding away behind the use of prescription medicine. I simply believe he has a lot of nervous energy and when he hits the stage he uses it. Even in the Jonathan Ross' Interview when he was showing his tattoo on his wrist I could see his hands shaking. I totally understand his symptoms because I've experienced it myself.