I haven't washed them yet! I've worked them more often than not but I always hang my pants up and wash all as little as possible, to keep the integrity of the original fit. My advice would be always cold wash, never high heat, and if you can hang dry or low tumble, to avoid abuse and shrinkage.
My top bottom was brutal at first - I never return, but considered it at first because the top closure was impossible. Honestly, I slipped my knife in the top opening and helped it a bit and they have been perfect since - no issues whatsoever.