2. Because There Is A Fine Line Between Love And Hate...
Another reason that babyfaces make the best heels is because they essentially betray the fans every night - and that betrayal is infuriating. Ever wondered why the person you hate most in the world is often a former friend or an ex partner? It is because you have to open your heart to that person and if that person in turn rips your heart out, then you are usually filled with legitimate, unavoidable resentment towards them. Its nature, its chemistry, its science...Or something. Viewers who have watched Cena work with disabled or dying kids (the one thorny issue with this argument, I must admit), or overcome diabolical odds solely by virtue of playing by the rules and hitting a firemans carry at just the right moment, would have every right to hate the character just as passionately if he no longer cared about charity work (although that would probably be a step too far in my esteemed opinion) and acted like a bully and a scoundrel at every turn. That love could very easily become hate and that hate could, if coaxed, become a very profitable business venture for Vinny Mac.