Help required with Nike XXX Black Denim

I hope this is the right place to ask these sort of questions.

So I bought a pair of Nike XXX Black Denim, I've worn them for about a month and after a couple of weeks they got this look. 

Can anyone tell me the reason this has happened? Or if I can "clean" them in some way? It's as if they lost color, but this happened at once and it kinda stopped. I'm not sure what it might be.

Thanks in advance, pardon me if I made the thread in the wrong place.

http://niketalk.com/t/15471/official-sneaker-care-maintenance-post-its-back

ask here