White was always the colour, or rather non-colour, of purity until it began to be classed as politically incorrect. At the beginning of this century a kind or generous person of whatever colour could be called a "white man". "Life," wrote Shelley in one of his less meaningful passages, "like a dome of many-coloured glass, Stains the white radiance of eternity." Shelley would have made a great copywriter for the soap powder industry. Actually candidus didn't mean white at first so much as bright, like a candle or candela. Cicero once described a fellow-orator as both brilliant (candidus) and colourful (fucatus).
You don't get much brilliance or colour in modern political debate, going by what is shown of Parliament, however you fiddle with the controls. Nor do you always get quite enough candour, at least in the word's original sense as the noun associated with candidus. Candour started by meaning brilliance and perspicuity, then purity of character, then absence of bias and coming clean. It also, in the 17th and 18th centuries, meant freedom from malice, but we've forgotten all that now. If in the coming weeks you hear a candidate starting a sentence with "Candidly" you can be fairly sure it's not going to be free from malice. Still, I don't suppose the Romans were any better, however togged up (the same word, by the way).