I find it funny, but disappointing, that the Republican reaction to criticism of Cain is to say, "but President Obama is bad too!"
First, I do not agree that President Obama and Herman Cain are fungible. Whether or not you like President Obama, he has always demonstrated an active interest and curiosity regarding foreign affairs, even if he hasn't always made the decisions I might have made. Cain, on the other hand, doesn't know that China has had nuclear weapons for almost 50 years, and, in this interview, says he would have handled the Libya situation better than President Obama but plainly has no idea what President Obama actually did, earlier this year.
Even if you think President Obama is stupid and incompetent, why does that make it acceptable to elect another stupid, incompetent candidate? You have at least a couple of reasonably bright, competent GOP picks - why would anyone choose an idiot like Cain?