Peter Vecsey brings the funny:
Jimmy Carter described as "careless" his remarks ("I think as far as the adverse impact on the nation around the world, has been the worst in history") about the George Bush administration. Ever the politician, Carter claimed he was talking about the Dolans, whom he referred to as "a bush administration."
Indeed. Realistically, it's hard to imagine any administration performing worse than James Buchanans. Such an administration's policies would more-or-less have to result in the actual destruction of the United States in order to qualify. I think Vecsey also makes sound points about Vince Carter.