Is there a minimum length for power cords?


A cable manufacturer's website states the following:

"However, any length shorter than 1.8 meters (5.9 feet)will begin to degrade the effectiveness of the shielding and filtering capabilities; regardless of who is the manufacturer. Power cords are not like speaker cable and interconnects where shorter is better."

Does anyone have any thoughts or experience as to the validity of this statement?
128x128owenlee
I have a 3ft Tara labs cobalt power cord, To my amusment, I sent Tara a E-mail asking about length of this model, Their answer?, The 3ft cobalt will have more resolution period than a 6ft cobalt power cord., that was their answer, However, I can tell you with 515 hours of burn-in that I have now, This power cord is not at all forward sounding, it's presatation is ideal, nor is it recessed, evadently, power cords seem to be different than say, a real short speaker cable where the sound does become forward, as far as speaker cables, I like 6ft speaker cable sound., cheers.
I bought longer than needed MIT Oracle PC's. I have been "so" grateful for the flexibility provided.The bit of extra length-on occasion-has "never" been even the least consequential--but it has been very revealing/informative/satisfying to be able to experiment due to having a bit of slack. Isn't that a common request.. to cut one some slack.
Why would length make a difference whether it's a power chord or speaker cable?