Given the choice between a crook and a sleaze, you'd normally think people would opt for the crook. Crooks can be très charmant, like Cary Grant in It Takes a Thief or, more recently, Matt Bomer in White Collar.
Crooks can be virtuous, like Robin Hood, which may be how Clinton sees herself: Bill and I cut corners so we can win power and use it to do good. Why is she the crook here, although Trump, too, has a long record of crookedness and there are obvious crossovers by both? Because she's the one named by the U.S.'s number 1 cop: the big G-man himself. The FBI targets crime, not sleaze.