@bobhaugen I'm not trying to be contradictory, just trying to figure out the disparage between the stories you tell and what I've seen myself. There are thousand year old cob houses in Ireland whose only maintenance has been regular updates to their roof and a lime wash. I have to expect that earthen structures are suitable to wet climates, they just need appropriate considerations.
Any organic material and mold also settles on dust on any other material. Doesn't matter if it is connected to the floor or not.
You mentioned a dome. It's possible that only vertical structures are appropriate for rainy climates...and also not being in a flood plain where the house would wash away. I'd also imagine that a yearly brush down to remove dust and grime if not a fresh coating of adobe/lime would be useful. Alternately one could go the sod route and use a living system to maintain the integrity of the earth wall, in which case the addition of more organic matter is a bonus.
I built a rocket stove with compressed earth blocks with some added magnesium-cement stabilizer and put it on a stone floor with washed gravel under it, under a roof, and it started to crumble the first year.
A stove is an entirely different beast, it goes through thermal cycling quite a bit more intense the a house would. From my understanding, from the few cob ovens that I've seen built and used, is that you try and build a more insulating vessel, utilizing straw, sawdust pulp or perlite to reduce the thermal conductance. The material is often brought to the bisque phase of firing so that the organic material is burned out resulting in empty space increasing the insulating properties. Rammed earth might have been too compact and rigid...a great thermal mass, but likely to conductive to not undergo thermal stress. I've also yet to see a cob stove that didn't have some cracks that weren't built with refractive liners (metal barrel or bricks).
All said, I agree with you. Don't build a traditional english A-frame house in the desert where the attic will trap too much heat and the wood and latex paint will degrade rapidly in the sun...and don't expect your wattle and daub construction to stand up to rain.
I'm sure your methods of dealing with dealing with human and animal dung (ie composting) wouldn't work in a dry environment where the dung just dries out and sits...instead burning it as a fuel might be a better solution...something that would never work in a wetter environment.