"It raises an interesting questions; at what point should we consider it to be "pristine"?"
This a very good point actually. Just like you said, way too many natural places around the world have already been modified by humans and the very original, pristine wilderness might now be restricted to just several small areas. Which is sad in my opinion. I generally don´t like it when people interfere with nature too much. In my country, for example, we have been having serious problems with the bark beetle because decades ago, during the communist era, then environmental "experts" were, for some reason, planting only spruces and when the bark beetle disater struck now, the entire forests have to be cut down. Typical example of human interference with nature going wrong.