Important:In GoldSrc, Due to how lightmap smoothing works, dlights will always act flat shaded even on smooth-shaded brush surfaces.
Code Fix:If using a custom renderer, the VERTEXNORMALS or FACENORMALS BSPX lumps can be used to preserve smoothness data for dynamic lights.
Confirm:This is probably fixed in Source, which has a vertex normals lump.
Bug:In GoldSrc, dlights do not work properly on surfaces that aren't set to 1.0 texel scale (a bug inherited from Quake). This is best demonstrated by the glow from active Quad Damage in Deathmatch Classic. [todo tested in?]