I've just been sweeping the poop off. They never pee on mine and with their poop at proper consistency it doesn't stain either. It's no different than the houses I have which have been in use for several years. I have new houses and a mountable house with platform coming but I have no plan to replace the current houses yet. These will go in cages that still have plastic shelves or cheap petstore houses that barely fit a chin and flip easily from the cheap, light material. I do need to pull a couple nails that have become visible on 2 houses we have. We only have the tools to make plain board shelves so I have to order the houses and fancier shelves.
If you have an illness or the wood becomes dirty I would sand it, spray with bleach or vinegar, and lay it in the sun. Both bleach and vinegar evaporate to leave nothing harmful behind and sunlight kills as many germs as any disinfectant solution. It's a pretty standard way to disinfect many things especially absorbent ones. If the bleach smell won't go away switch to vinegar which will neutralize bleach and then completely evaporate.
