i have had good results with ,dont laugh, boot polish,not the paste type but the liquid type for scuffs etc.squeeze it on a brush then apply to the bad spot ,buff off & there you go. it seems to last & you can get it into the hard to reach areas with a cotton bud or similar. my engine had dull areas & bad water stains after being stored for years outside.t cut etc only lasted a few hours till it went dull. the boot polish has been on a couple of weeks & still looks good .
not a fix for a mint show bike but easier & less notiecable than paint on a daily user.