If you choose to keep them it is easy to make them look better then new again. A simple vibrating tumbler, ceramic media, lemishine (citric acid) and a splash of water (just enough to make it damp) will make old dirty bullets look better then new again.
I use this technique on the bullets I make and I'm certain it will work for you. Check out this link for further details should you wish. If you choose to try it out use only a 100-200 bullets for first attempt.
Secret to making better more accurate bullets!