Turd polishing: The act of trying to make something hopelessly weak and unattractive appear strong and appealing. An impossible process that usually results in a larger, uglier turd.
A recent popular word in chinese is '屎上雕花‘, yes, it's very ugly, so let's say another word "put lipstick on a pig', that Barack Obama told a crowd at his campaign event in 2008.
His original word is "You know, you can put lipstick on a pig", then he said, "but it's still a pig.”