The problem with black anodized components is really with the wear surfaces. Like at the teeth of chain rings that never really wear out to silver evenly. The spider and crank arms can get beat up too with scratches that really show up bright silver scuffs, marks and scratches, but to some extent you can avoid such if you are careful to not bang around you bike and make sure your pedal, shoes and straps are adjusted correctly so they do not rub against the arms when pedaling, wearing out the black anodizing at points of contact. There are some manufacturers like Rino that made chainrings with black (other colors too) anodizing just at the non-wear areas (teeth are silver), so they look good longer than other dark anodized chainrings. They could be a good alternative to stock black anodized chainrings.
Black anodizing can also fade to grey from exposure to UV. There's really no getting around that other than only cycling in the dark or under leaden skies....