My vintage stuff stays very clean, mainly due to limited use. The more modern stuff gets dirty, and typically stays that way. Drivetrain maintenance on those is kept up. Dry chain lube is key.
__________________
My bikes: '81 Trek 957, '83 Trek 720, '85 Trek 500, '85 Trek 770, '81 Merckx, '85 Centurion Cinelli, '85 Raleigh Portage, '92 RB-2, '09 Bianchi