You should know exactly what to expect both indoors and outdoors in terms of repair and maintanance and their costs. A fresh coat of paint could be hiding serious structural problems. Water marks in the basement may indicate a chronic seepage problem or may simply be the result of a single incident. The home inspector interprets these and other clues, then presents his professional opinion as to the condition of the property BEFORE you buy, so you can avoid unpleasant surprises afterwards.