excerpt from the Soil Report Newsletter of Soilmoisture Equipment Corp.
You've heard the expression, "I cleaned up," meaning the person made a killing at the track or wherever, obtaining lots of money, maybe all there was to get. You've also heard the opposite expression, "I was taken to the cleaners," meaning a person lost everything.
Both expressions have nothing to do with dry cleaning, laundering, or custodial services. They have everything to do with agriculture, especially harvesting. The word has been lost in the modern era of combines and such, but for centuries to "clean" meant to harvest thoroughly, leaving nothing for anyone else, even the birds. In the days of scythes, sickles and such, fields were poorly harvested, allowing the less fortunate to come in and scoop up some of the crop for their own use. A person who "cleaned" his field, took everything, was considered uncharitable. Today it's simply good farming.