Are manufacturer AC cables good enough?

My "thinking" and experience have been at odds when it comes to AC cords. Thinking tells me that "wire is wire" and so long as it can carry enough current, it can't possible sound any better. My experience is the polar opposite. In every case, no exceptions, upgrading from the stock power cords has dramatically improved my enjoyment of music. Maybe my "system" was no better, but the music was most often far move involving, emotionally engaging and just more real. Switching AC cords worked on a Rotel CD player, ARC Ref 3 preamp and perhaps most dramatically, on a McCormack DNA 1 Platinum revision amp. I have seen vastly better picture quality on a plasma TV, heard more detail from an ARC LS9 preamp and on and on. There is science (better understood then in the past) as to why good AC power cables do what they do. The merits of all sorts theories can be debated. I have decided just to ignore the science, for the most part, and the debates, and simply enjoy the music.