Converting Power Cords into Speaker Cables?

Someone very knowledgeable in high end audio swears that instead of buying more expensive speaker cables, it's more cost effective to look for power cords of the same cable and use it as speaker wires. He has very successfully done this with Vahalla power cord and found no sonic difference between the original Vahalla speaker cables and one he made from Vahalla power cord. He is now applying his creativity to other brands. The advantage is considerable cost savings but downside is when you want to sell these reconverted cables. Your views are appreciated. Anyone tried this trick? Any technical/cable geometry flaws in doing this?
lall