When you open a Smart Object Layer's Object Photoshop creates a temp Work Documents in users system temp space. Those files persist till you close the document with the smart object out of Photoshop. The temp work file are not in Photoshop scratch space. On a windows system the would be in "C:\Users\(your User ID)\AppData\Local\Temp\" Which is normally on your boot disk. You can change your environment though your system variables.
