I think you touched on it but there is some reasonable compromise. Dirt on the floor mats and basic cleaning should be included, but if you are spraying champagne on the walls it would be reasonable not to be included. Where do you draw the line. If you want to charge for the "worst case" it will inflate your prices dramatically. If you charge for the average then people are basically incentivized to be unnecessarily messy. Of course many hosts will be unreasonable and charge extra for the very basics that should be included.