One thing an inspector should look for is failed thermal-seal windows. Sometimes they can be hard to spot, depending on how cloudy they have become. Another factor that can make it hard to identify them is the general cleanliness of the windows. More than once, I have found myself trying to wipe a window, both sides, just to see if it cleaned up. When looking for failed windows, hard to see locations can include skylights and windows that are high off the floor. One essential place to look, because it can be more costly to replace them, is at sliding glass doors. In the photo below, you are looking at a condo at Point Roberts that looks out over the ocean. This fogged slider is at the upper deck in the master bedroom - not the place to have a fogged window. Today there are companies that can repair many of the fogged thermal-seal windows and, of course, replacing them is still the old-fashion option
Thanks for looking.