Katsbits.com use the sculpt tool to make a house look a LOT older.
From the tutorial:
‘Ageing’ a model is one of the more tricky aspects of 3D, making it looked ‘used’ in such a way that it appears natural and random, like its falling to bits under its own weight; normally this would mean some extensive work in edit mode, pushing and pulling groups of vertices which can often look a little forced or contrived. Fortunately, Blender 3D’s ‘sculpt’ tool comes in handy as an alternative way of doing just what’s needed.
Link
