Despite his charismatic appeal to the average Joe, Joanne, and assorted Gennifers and Monicas, Clinton was done in by Americans' suspicion of smartness. Clinton wasn't helped either by an educated First Lady who lacked the common touch. You see, America is fundamentally anti-intellectual. Americans en masse are at ease with a man who shares their low ambitions for intellectual achievement. The office of the US President necessitates quick and clear decision-making.
Stupid Presidents make quick and clear decisions.
There's no Hamlet-like moments of indecision. They don't sweat the finer details of policy, as do smart Presidents. After all, Carter was a nuclear physicist. Carter, however, was one of our least effective leaders. He labored over details.