Also, Newt is not exactly the most likeable guy in the room. He's thin-skinned and takes things personally. Conservatives who win presidential elections tend to be likeable, not perpetually angry. Reagan, for example, even George W. Bush.
Compare that to McCain, an obvious prick. Bob Dole, in real life apparently a good guy but came across on TV as cold.
You can see Romney straining to project likeableness. Cain seems genuine because he exudes it. Perry, not so much.