How McCain treats his wife (from Rolling Stone article, pg 8)
During his 1992 campaign, at the end of a long day, McCain's wife, Cindy, mussed his receding hair and needled him playfully that he was "getting a little thin up there." McCain reportedly blew his top, cutting his wife down with the kind of language that had gotten him hauled into court as a high schooler: "At least I don't plaster on the makeup like a trollop, you cunt."
According to McCain's GOP colleagues (also from Rolling Stone article, pg 8)
At least three of McCain's GOP colleagues have gone on record to say that they consider him temperamentally unsuited to be commander in chief.
Sen. Thad Cochran of Mississippi weighed in that "the thought of his being president sends a cold chill down my spine. He is erratic. He is hotheaded."