I agree with David. Very few of us have the time, ability, and/or space to model an exact replica of a given area, location or site. Therefore we are strive for a "sense" or a "feel" of what we are trying to model. You can't model, for example, the Rocky Mountains. So you create a model that inspires a "feeling" or a "mood" that reminds the viewer of the Rocky Mountains. I model small towns in the Rockies during the transition era. These towns had mostly seen the end of the boom times and were all very run-down. I model the Rocky Mountains, but I also model a railroad struggling to succeed after the boom has passed it by. If everything comes together, those viewing my layout come away feeling like they were there. So yea, I model a mood.