I’m not a fan of either Hillary Clinton or Joe Biden (or any candidate from either party for that matter), but I don’t really see any particularly hypocrisy here. First, as Ethilrist points out, maybe he just thinks he’d be a better president; I don’t think the general idea is that someone runs for president on the idea only that they’d be less corrupt.
And as for Obama’s scandals, there’s always scandals, the president and his staff may or may not have any direct knowledge of them, but they generally do, and for the most part should, shoulder the burden for them. That said, some of the stink, whatever there may or may not be, of the scandals associate with Obama will rub off on Biden, but not all of it; he has some deniability being the VP on a lot of them. Whereas, many of the scandals associated with Clinton are directly tied to her since the beginning.
Further, in general, I think the electorate is more familiar with the scandals associated with Clinton and probably thinks they’re worse, or at least in the familiarity with them, have been told they’re worse. People are familiar with Bengazi, and Clinton bears as much or more of that blame than Obama and, thus, more than Biden. That’s not to say that, in a general election, whatever can be blamed on Biden would be. After all, in a general election, dirt on whoever is running WILL come up, Democrat or Republican.
The one benefit I see in Hillary’s favor regarding scandal is that a lot of it has already been played out and the reaction of the public is generally well known. I have little doubt Bengazi or the emails stuff would come up, but both parties know the reaction and can plan accordingly. And, to a large extent, many of those scandals are already old news and won’t have much bite anymore. Biden is an unknown quantity. I think each party has a rough idea how much he may or may not get blamed on him. But, after all, how much did Gore get blamed for scandals under Bill Clinton or Bush I get blamed for stuff under Reagan; not all that much.