I love these headphones, as well as the MDR-V600 headphones.  I believe the oil from your skin over time will cause the coating to slough off of the earphone padding skin.  However, since hygiene is of utmost importance, especially if more than one person is using the headphones, I have purchased some sanitary headphone covers.  This not only keeps the headphones clean, it also makes the headphone ear pads last forever.  Just an idea, but try using sanitary headphone covers on ALL your headphones.  I believe you can buy a bag of 100 on-line for about $18.00.  It's definitely worth protecting these wonderful headphones.  I use them in my home studio, and the frequency response is excellent, and I can hear every note, not to mention the exceptional large drivers (50-mm) that the headphones contain.