The President in particular is very much a figurehead -- he wields no real power whatsoever. He is apparently chosen by the government, but the qualities he is required to display are not those of leadership but those of finely judged outrage. For this reason the President is always a controversial choice, always an infuriating but fascinating character. His job is not to wield power but to draw attention away from it. On those criteria Zaphod Beeblebrox is one of the most successful Presidents the Galaxy has ever had -- he has already spent two of his ten presidential years in prison for fraud.