To me it looks like the scales were scuffed and he has ink stuck in the scuffs. You might try a damp towel and actually see if it comes off. You are in a better place to judge that we ever will be from pictures. Does it look like it will come off?
Is there something abrasive like the edge of a plastic hide or the lip.
It doesn't look like scale rot to me, don't use polysporin it can soften the scales and compound the issue. 1% Betadine Solution and a 20 min soak would be a scale rot treatment, but I would not suggest it actually is scale rot.
I have two males that play the try to fit on the lip over the door and they too often fall off with a bang.
Unrelated topic, a IR gun, aka temp gun, cannot measure air temps. If it could it would be useless only measuring the temp of the air in the body of the gun in your hand. It only measures surface temps and even then does not accurately measure clear or translucent objects well. It is best used on dull (non glossy) medium dark objects (brown paper bag is the perfect emissivity). Metals as also often cause incorrect readings (and metal pigments in paints and plastics) too. They are a fantastic tool but as with all things the user needs to know the limitations of what they use.
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