No. There have been many that could be considered corrupt, especially many prior to the 1900's when many positions were directly appointed by each administration by the President himself. Of those, when tarriffs were enforced, Corruption ruled in the ports of New York and New Jersey, whose federal overseers were named by the President, Garfield was even assasinated over the naming of positions. Also, the Jackson Administration, as successor to Lincoln, was accused of much corruption in managing the reconstruction of the Southern States after the Civil War. LBJ and the management of Vietnam and the war, while hidden largely from the people's eyes also festered much corruption in that country, the horrible management of the war and war profiteering, including outright murder, and defense contracts that benefitted members of Congreww and himself personally.
So there you go. the Obama Administration may not have been the most corrupt. It most definitely was the most inept, but not the most corrupt. (close, with Clinton involved tho.)