"The success of Berlusconi is thus not a blip or an anomaly, but goes to the heart of Italian culture, and reveals the widespread disbelief in Italy that politics could ever be cleaned up or made remotely fair. So Berlusconi’s insistence that the criminal charges against him are merely trumped up by his enemies finds fertile territory; even those who oppose him are willing to assume that an element of persecution is involved, as if what mattered were not his guilt but the spirit in which the investigation is carried out, since every politician is presumed guilty one way or another and it’s common credence that no action on any side of the political spectrum is ever genuinely undertaken with the public interest at heart. Many people are actually rather comfortable with this state of affairs insofar as it justifies their own small misdemeanors and tax evasions. Hence, if the judiciary prevails and Berlusconi is excluded from political life, millions of Italians will see this not as the affirmation of a rule of law (something that might make life more challenging for everybody), but simply as one battle won by the other side. In short, the polarities good/evil, moral/immoral, or even effective/ineffective around which we suppose that politicians should be assessed and judged are always subordinate in Italy to the overriding question of winning or losing, which is absolutely the only thing that matters."
—Tim Parks' "Italy Held Hostage," is both brief and great and answers the vexing Berlusconi question as best as any explanation can.