Romex wiring found in many buildings actually works quite well. So it really becomes all about that last few feet and also how well the power cord is terminated- molded cords generally are not terminated very well.
Ralph (Atmasphere),
Are you saying that a power cord made from Romex with quality terminations would make a great power cord if you can deal with the stiffness? Would you recommend twisting, braiding, or leaving the conductors parallel?