Without a good foundation, the rest doesn't matter. Hire a Home Inspector to go in the crawl space to help you look for clues of damage in the concealed areas. If the crawl space or basement looks, smells, or feels damp or wet, you need advice on how to dry it. Standing water is surely a sign of trouble. Cracks or obvious settlement in the foundation or basement wall should be referred to a Professional Inspector or Engineer for evaluation. Rust or rot on basement columns indicates wetness. Look closely for rotted framing. Rot can be tremendously expensive to repair. As you check the exterior of the foundation notice the fireplace or chimney. Is it leaning away from the house? It shouldn't be! A properly built slab floor should be reasonably warm, dry, and solid. Check for slab cracks.