Sometimes shoes get so dirty and stinky that they can't be used. They aren't really worn out, just gross. When it comes to that, I'll throw them in the washing machine. The sandals shown are even suede leather. They turned out fine. The worst thing that can happen is the shoes are ruined. They were worthless to me without washing them anyway. I usually air dry the shoes, though I've heard a couple of shoes in the dryer with some towels makes the towels really fluffy. Putting some old towels in the washing load helps get the shoes cleaner too (more stuff to rub against.) Hmmm, towels and shoes have a symbiotic relationship...who knew?
Ooh, my other tip is that saddle soap makes Crocs look almost brand new. And a drop of tea tree oil on a baby wipe can be used to clean the footbed of stinky sandals.