WordNet sense 1 (having lost or been caused to lose interest because of overexposure):

benumbed

WordNet sense 2 (not having or showing interest):

uninterested

WordNet sense 3 (made dull or blunt):

blunted

WordNet sense 4 (not having a sharp edge or point):

dull

WordNet sense 5 (deprived of color):

greyed

WordNet sense 6 (weak in color; not colorful):

colorless, colourless