Hi... the most unpleasant or roughest aspect of life. (A reference to the inside of a garment where the seams show.) Doctors in that area really see the seamy side of life. Mary saw the seamy side of life when she worked as a volunteer in the homeless shelter.

'Seamy' is an adjective meaning 'unpleasant'. This type of work (a work that involves giving help to people in society who have problems because they are poor, ill, homeless, etc) makes the workers see the most unpleasant or roughest aspect of life.