Among his other jobs, Herman Cain has been a radio talk show host. This is not, in itself, a qualification to be President (though being a talk radio host strikes me as a hard job), but it was an opportunity for preparation to be President. This is to use Ross Douthat's definition of preparation as "the hard work of scaling up one's understanding from state-level challenges [or in Cain's case the opinions of a politically interested businessman] to national issues that any aspiring candidate needs to do."
As a talk show host, Cain was, in a sense, paid to think about public issues and then talk about them for three hours a day five days a week. From my limited understanding, talk radio show prep tends to focus on the day-to-day, but Cain could have immersed himself in the best conservative policy thinking. He could have worked at making this thinking accessible to his audience. Cain seems not to have done that. Maybe he did and we just haven't seen it yet, and he is going to surprise us.