I know what you mean. I am never happier than when faced with a really interesting and challenging building defect, whether it's a beautiful raking crack, penetrating damp or poorly detailed cavity walling. To the owner, of course, it invariably means spending vast amounts of money, having a room (or a whole building) out of use, and all the disruption to their lives and businesses that only building defects can cause. To me - heaven! Ages spent picking over it with a pointing tool, happy hours measuring, photographing, mulling over it in the comfort of my office, cup of tea by my side...