That's the dilemma, Brandis. A good clean and an oily rag, but the parts that need paint will stand out. I'd avoid gloss and go for a sheen finish. All paint fades, black* can go to a sort of grey, some old ones a sort of green.
* and nowadays you've even got various shades of black. As the paint suppliers / mixers I use told me, you've only got to add one drip of another colour into a litre of 'black' and it's a new shade.