We studied the near-field optical properties of colloidal gold nanocubes (GNCs) using a photochemical imaging method. This method is based on the vectorial molecular displacements, of photosensitive azo-dyes, which are sensitive to the polarization of the optical near-field of the GNCs. We analyzed the spatial confinement of both electromagnetic hot and "cold" spots with a spatial resolution up to 15nm (λ/35). The new concept of cold spot presents valuable and complementary electromagnetic information to the well known electromagnetic hot spot. We demonstrated that cold spots are highly sensitive to polarization and can be much more confined than hot spots enabling them to be applied in high resolution imaging and spectroscopy.