All depends what you mean by a leer - my dictionary gives the definition as sly or lascivious or malign. I'd say that "sly" just about fits that expression of his, and the song pretty clearly rules out "lascivious".

That's why, when I introduced the word into the thread I called it a "sardonic leer" - "bitter, scornful, mocking, sneering, cynical". But with a humourous touch, because he's parodying himself. As he always has been prone to do.