www.alphadictionary.com

"Shoddy" had its origin in the US Civil War. From the NYTimes ("King Cotton and His Bloody Surrogates" May 5, 2014):
"Manufacturers mixed old wool with new to make cheaper cloth. Recycled wool was known as shoddy — a word that permanently entered the language after the “shoddy scandals” of 1861-62 revealed just how shoddy that cheap cloth was."

To bad no one seems to know where the term originally came from. Probably some slang in the industry that caught on but was never written down.

An older related term I came across while looking is mungo.