Build your house with a solid foundation

What happens if you put a structure on a poor foundation? There is an increased risk that the structure will fail in one way or another, right? It helps to know what your soils are like, what trees will tolerate those conditions and plan accordingly. What is the drainage like? Do you need to do some soil amending, or plant some cover crops? Do you have subsoil with a skim of nice chocolate loam imported from afar?