So I have AKG K712 pro ordered back in 2017, which came with these earpads. They must be a big part in why these headphones feel so incredibly comfortable to wear. They're just like memory foam pillows and they never make me sweat and feel the weight of the cans.
And just like any velour-coated earpad, they gather gunk quite easily and it's pretty much impossible to get rid of it. I've tried washing the earpads (after removing them from headphones of course) by scrubbing and soaking them with gentle shampoo made for wool. There was some effect, but the gunk has sadly got too deeply embedded, so a new pair of these earpads was still necessary.
Why I went as far as to wash them? - the price. : ) a pair of these is almost one half of what these headphones cost. While the price is somewhat understandable, it has been a tough bullet to bite when you don't have a lot of free money.
The price is fortunately reflected in the quality of the product, as even the washing didn't cause any of the glued parts to get loose. They would basically last forever with intended usage, if it wasn't for the gunk and grease buildup. In addition to construction quality, they look and feel wonderful. The price hints at luxury and that's what you get.
it's hard to imagine anything more comfortable than these earpads. They also seal very well thanks to the memory foam insides.