I found this hilarious instruction in the manual of a $6000+ VPI Prime Signature turntable:
"If you notice hum in the system, remove the turntable to phono section interconnects and replace them with very cheap, standard VCR interconnects. These are well shielded and should eliminate the hum. If the hum goes away, get quality, well shielded interconnects."
Notice that the very cheap, well-shielded interconnects are good enough to fix the problem, but have to be replaced immediately by "quality" interconnects!