Well we actually knew it, sort of, but the idiots didn’t listen to us
We knew of radical associations such as Wright and Ayers, a few knew of his avowed Communist mentor, and you’re right, what was known wasn’t heeded by the majority.
But when for example he told joe the Plumber before the election that “when you spread the wealth around its good for EVERYBODY”, he was expressing the Communist view that crushes the individual in favor of the STATE and the COLLECTIVE populace.
If that statement had been lined up with corresponding quotes from famous Communists, that inescapable truth about Obama would have lined up just as well as these Communist quotes line up with his “you didn’t build that, somebody made that happen”.