My model has a few vertices that shade abnormally bright, dark, or sharp that I can't easily correct by Shift+N -> Average -> Face/Corner. How can I correct these normals? Here, they're mostly around the lips, though the tragus has something odd too.
This image is updated from this one (which had a more receded browline).
UPDATE: I don't think it's a manifold issue, as the only non-manifold verts are those along the midline of this mirrored half-mesh. The 3D cursor was set to the center of the non-manifold verts; there are no errors in the legs. There are still weird normals near the nose/philtrum and the ear-head junction as above.