Because people are stupid, as soon as he mentions the name of their city.
^This. Or calling them "honest".
Cena is smart when it comes to manipulate the crowd and his haters. He knows exactly what he has to say.
Maybe manipulate is the wrong word... let's say he knows exactly what to do in some situations and how to play with his haters...
Like the thing with the "I hate Cena"-Guy or just stands next to some of his haters, let the people chant "Let's go Cena, Cena sucks!" ("All the girls and Kids go 'Let's go Cena!' and the Guys 'Cena sucks', come on!")
So... I would say he knows how to handle the crowd.