I read that in an interview with him way back. He drove the pup wirers nuts by sending what they proposed back, saying it didn't sound like what he wanted. In the end, he gave them the bass so that they could dissect it. And so they did to then report that it sounded the way it sounded because it wasn't functioning properly. And then built him replicas with the same defect. "I'm the only guy that has broken pick-ups expensively custom-made for him!" Dusty joked.
I had the same thing with my TV yellow (now there is a story to be told ...) LP Junior shape EB-0 you procured for me years back, its mudbucker sounded like no mudbucker I ever knew: gnarly and middish with no overbearing sublows. Until the day when it wouldn't sound at all anymore. I had it repaired and now it sounds like any other mudbucker from the era, with my luthier commenting: "That pup wasn't properly wired btw."