If the sewer line or drain line for a home you are buying crosses another property, make sure there is a recorded easement that will permit access to maintain or repair it. Without an easement, you would have to hope for your neighbor's cooperation, but you would not be able to count on it.
Bent nails often result from poor hammering technique. However, they can also be caused by a dirty hammer face, especially when using cement-coated nails or working around adhesives. If you have problems, occasionally run a piece of fine sandpaper or emery cloth over the face. If you keep the face clean you will gain more solid contact with the nail and will avoid black marks on the wood caused by a dirty hammer.