For you strikers out there

I have watched tens of thousands of rounds of sparring in western boxing, Kickboxing and Muay Thai. One thing that I have noticed is for the large part, Thai fighters dont get cut. I have seen elbows blast them in the face tons of times, and they dont bleed at all. What is the deal? Do you think that it has anything to do with that liniment that they put on their faces? If anyone has any insight, help me out please.