I have used the heatshield for just few months but the stains on it was really shitty. It must have been from the engine degreaser that caused it.
I polished the heatshield for 2 rounds and im done already. One thing about aluminium surface, they are really prone and sensitive to sratch marks. You have to handle them gently that is if you want it to be spotless.
In my case, it was more of a functional purpose than bling-bling. I dont mind the scratches.
I cant imagine having an electric buffer. He he.