I had a skin analysis done very recently at a Biotherm event. The beauty consultant used this device to measure the sebum levels on both my cheeks and ended up looking very puzzled.
She did the test twice and then asked me a very strange question. Did I sleep with my right side facing the air conditioning?
My surprised answer was yes.
Apparently, the right side of my face has lower sebum levels than the left side of my face i.e. the right side was drier. I found this absolutely fascinating!