I don’t know. I’ve looked into this a lot of times and there definitely seems to be a consensus among people with more experience than me who say if the noise you hear when you plug the bass and goes away when you touch the strings that means the grounding is working correctly. Now certainly some bases are noisier than they should be which is when you can look at shielding. This is how I understand it, but it’s also possible I’m wrong.You may be right. It seems to me that if the hum is gone when you touch metal on the bass it means it's being grounded through you instead of through the cable.