Moved to new place (Europe), no nice butchers around, only store found has chickens with yellowed parts like in the attachment. I never seen tint like that on a chicken and wondering what does it mean?  
Yellowing (particularly around the hocks) can be an indicator of the breed, and is more prevalent on younger chickens. For females it can fade as they reach laying age, although diet (high in corn) can also keep the yellowing. 