  Recent renewed interest in the mixed valent insulator SmB6 comes from
topological theory predictions and surface transport measurements of possible
in-gap surface states whose existence is most directly probed by angle-resolved
photoemission spectroscopy (ARPES). Early photoemission leading up to a recent
flurry of ARPES studies of in-gap states is reviewed. Conflicting
interpretations about the nature of the Sm 4f-5d hybridization gap and observed
X-point bands between the f-states and the Fermi level are critically assessed
using the important tools of photon polarization and spatial dependence which
also provide additional insight into the origin of the more ambiguous
{\Gamma}-point in-gap states.
