For me, washing the kneepads and wristguards never got close to all the stink out.
I read an article about trying hydrogen peroxide in the laundry, but that didn’t work, though I possibly used too little. I didn’t want too much, or to spritz it on, as I was afraid of hydrogen peroxide’s bleaching and possible deteriorating effects on the fabric (and my skin).
Then I tried putting rubbing alcohol about 50/50 with water in a spray bottle. Now I take off the pads and lightly spritz the sweaty side, then hang them up to dry. The pads smell a LOT less heinous; (they still smell a little if you actually sniff them, just not from across the room). The alcohol seems to kill the bacteria and then it just evaporates.