I've seen this problem a few times - its down to flux modulation and virtual inductance. This is caused by the thermal capacity of the fibre and linear alignment to the utility fusion within the house (eletrical junction/fuse box) The field flow of the electrical charges causes amplitude reduction throughout various areas of the house. This causes flux distortion and opaque refraction, hence the lighter marks you see in the photo. In short, its fooked!
Seemples!!!
Huh ? Was any of that for real , lol 
might distort your hifi speakers perhaps but the carpet ! ?
Nah, im afraid not. I just had a bit of fun with an online "random technology phrase" generator. Got you thinking though!!!