Seamy means ugly in a moral way: full of crime, violence, or dirty secrets. People often say the seamy side of a city or of a business — the part that looks fine from the street but is rotten if you turn it over. The picture comes from clothes. A seam is the line where two pieces of cloth are sewn together; the seamy side was the inside, where you see all the rough stitches, not the pretty face. Writers borrowed that for the ugly underside of life. It is a bookish, newspaper kind of word; in speech people more often say the dark side or the ugly side. It has nothing to do with seem (to appear), though it looks close.

醜惡的、陰暗面的