hey thanks there mate, much appreciated and happy you noticed because it is something I have been putting effort into. Its not a big thing in the sense that its well planned.., no! Its more just very subtle and completely random as it is in life. I figure if the wear and damage is too much, unless its a war zone or semi war zone, then someone will fix it. Theres a limit to the amount of wear one can put in a scene without it looking 'on purpose.' mostly I put it into 'vertice mode' (depending of course on whether its polys or nurbs) and just push the a fraction. if theres somewhere that I 'feel' needs some wear but theres no verts.., I add resolution for that reason and push the verts.., i dont think I have ever puled verts for wear, but im sure that would crop up in certain situations.., the 'sculpt surface tool' is great for that too.., particularly the corners.., I used it on the bricks.
take it easy and life will be easy