This is a tutorial showing you how to make a fingerprint and smudge texture. This is the kind of thing a 3D artist would use to add some surface imperfection detail to shiny surfaces. I'm using subtraction to get very clean, high quality results.
My texture pack: https://artstn.co/m/rbXJ
My Artstation: https://www.artstation.com/robblight
My Instagram: / blightrob