In my opinion, it's not that big of a difference, but still easily noticeable. It glides better when it's clean, but when it's dirty it has more resistance although it still glides fine if you swipe all the crumbs and small dirt off of the mousepad.
And as I previously said, it doesn't really bother me so I haven't properly washed this mousepad yet (even though I probably should). Simply said it's a great pad, but it just requires more maintenance if you want to keep it properly clean and closer to what it is when you first take out of the box.
GL finding the perfect mousepad and hope this helped! :)