Use real dimensions
Write down the width and depth of the furniture you plan to keep. Place those measurements on the floor plan rather than relying on tiny marketing illustrations.
Include door swings, wardrobe doors, pulled-out chairs and enough space to walk around the bed. Check where a television or desk can go without blocking a window or doorway.
Check the physical room
At the viewing, measure the walls you depend on and note columns, radiators, sockets and unusual corners. Ask whether large items will fit through the lift and apartment entrance.
A room works when the furniture fits and people can still move comfortably. That is a more useful standard than an empty-room photograph.