Logical possibillities .....the 'firmware' (the operating programme of the digital camera) could be 'corrupted' which could cause intermediate problems or conceivably certain items/subjects (because of colouring, lighting conditions etc etc) may result in poor pictures. If the 'part ' of the firmware corrupted relates to say 'automatic lighting adjustments' then it is quite likely a reflective surface/colour may highlight the 'fault', yet another 'subject' may not.
Non-Logical possibilities....there has been documented cases where some objects/people photograph poorly....irrespective of the camera used.
I will try and dig them up......needless to say...supernatural explainations were offered as science had none (at the time)....starting to get a bit like a X-file........Mulder....if you're out there
