Clinton's weaknesses as a candidate are that she isn't a good campaigner, she's not naturally likeable and she doesn't choose great people. Mark Penn sucked at running her last campaign. Her campaign was slow to react to Obama's and really got whipped. But then the Obama machine was pretty incredible at campaigning.
Scandals and gaffes are what the media tries to sell. It's garbage. Is there one person in the country that said, "I was for Romney until I saw that 47% tape" or "I liked Obama until he made that guns and religion crack"? I doubt it.
Presidential campaigns are about demographics and turnout. Can the democrat turn out enough young people and minorities? That's about all there is to it.