Not with a pitch black, but "back in the day" I've seen many balls suffer from a thing called core seperation.
That is where the core comes loose from the cover material. And yes, it made the balls sound different, and gave them a "hollow" sound compared to the same ball that had not seperated.
A guy here was VERY good at finding them. He would tap on the ball with his wedding ring, and the ones that had seperated gave him a distinct, dull, "clunk" sound.
Might not be your problem, but it is possible.