Keep polishing 'em, really. Good lacquer works for a while, but eventually lets moisture in. Aluminium is a bit like brass in that respect; you can buy lacquered brass door furniture, but after two years outdoors it looks terrible and you have to apply paint stripper to remove the remaining lacquer and polish regularly thereafter.
Road salt makes aluminium quite blotchy, and in some parts of America they can't even comprehend the problem because they don't use it.
For hubs, have you tried the old CTC trick of a short leather saddlebag strap round the hub shell? The weight of the buckle stops it rotating, so it constantly polishes the hub when riding.