Well, the purpose of the 14th Amendment was to override the Dred Scot decision of the Supreme Court, and the 13th, 14th, and 15th amendments did make the Federal Government the guardians of the black people of the South. The white people of the South blamed them for putting them under military rule and corrupt, Chicago-style government for almost ten years. Instead of co-opting the many decent black people in the South, we did create a kind of apartheid state and gave them no share at all in the governmental and economic affairs on the state, except as a kind of helot. On the other hand, Booker Washington tried to make lemonade out of lemons by blacks in the skills of they needed to prosper economically, and a large number of black folk did manage to create a life parallel to that of the whites. But the general effect was to make them a sub-culture who as a rule simply did not have the opportunities they needed to prosper. Of course, neither did most white Southerners. The South did not really recover substantially from the aftereffects of the Civil War until after WWII.
Actually, the notion that Reconstruction governments were particularly corrupt is mostly BS spun by pro-Confederate “Lost Cause” apologists. It would be more accurate to say that Gilded Age governments generally were rather corrupt by modern standards, whether North, South, East, or West.