A reflection -can- be brighter than what you see. It's pretty much required by the laws of geometry. (Angle of reflection = angle of incidence.) When the light is behind the viewer, as it is in Niles's picture, a ray of light hitting the table will be most likely to bounce into the mirror and then into your eye (as in the left image). The only way it can bounce -directly- into your eye is when it hits just right on the front corner of the table (right image), which explains why the corner is bright.

My python page
My ShareCG freebies