The "Bradley Effect" is a valid factor. Bradley's competency is questionable. He was a police Lt. in the LAPD, who took law school courses at night and became an attorney. When he left law to take political office, I knew a lawyer who took over some of his cases, and couldn't believe the ineptitude of Mr. Bradley.
Bradley would speak before black audiences and exhort them, and before white audiences with a completely different demeanor and story. He sold the black community short as despite their enthusiastic support, the payoff was limited to a few concessions at the Los Angeles International Airport. Bradley played ball with the establishment, rhetoric to the contrary.
His family was a disaster. He had a brother who was the other side of nuts, whom he was always running after and extracting from situations. The family had been raised on welfare. Bradley was a "nice guy," who exhibited great strength of character in extracting himself from the environment in which he lived and aspiring to greater accomplishments.
Our perceptions of politicians are often distorted. I had a man working for me, who was elected to the California legislature, first the House, then the Senate. He was one of the few people we almost fired for gross ineptitude, an inability to do the job. We usually found some slot for incompetents. It was difficult to place him. He was such a "nice guy," we finally kept him on as a supernumerary of sorts absorbing the cost.
Fortunately, the union set him up as a candidate and campaigned for him, and he won, so our problem was relatively short-lived. The crux of the story was that I came across two old ladies discussing this fellow, who were enamored of him and overwhelmed by his great oratory ability, great itelligence, and dynamism, excitedly discussing his virtues. The public persona and an insider's evaluation of competency differ greatly. But then there is the Obama phenomenon. It is an old story, oft retold.
Keep in mind that after the tumult and the shouting die, we each put our pants on one leg at a time, and these exalted evaluations of public figures are projections and seldom approximate reality.