If they pass the bomb test, the electrodes aren't burned out of shape, the porcelain is in good shape (on the hot end, or in the harness tunnel) just make sure they are cleaned and properly gapped and fly with them. If you are worried about cosmetics, then shoot a little engine paint (after scuffed and cleaned) on the body - but not near any thread, top or bottom. Color - your choice. 500 degree engine paint is available at NAPA, autozone, etc. Keep the paint away from the threads, the electrode end, and the harness attach area.
