I saw that train set last week and I almost had a heart attack because at first I thought it was covered in graffiti from the top down. Now that would have pissed me off. I could even imagine how angry the MTA would be since useful money would have to be wasted to remove all that.
It took me by surprise, but overall I think it looks kind of good. Better than ads pasted on windows. Plus, this R142A set reminds me of other transit systems that do not show a metallic exterior. And even if it did look ugly to many people, the only thing that matters to the MTA is that it brings them money. Considering their money problems, this would be a very good opportunity to allocate more funds.
And yes, the stainless steel cars in the New York City Transit have a body made of metal - it is not called a "silver paint scheme".