On December 14, 1965, Donald J. Gribble and Henry E. Bennett received U.S. Patent No. 3,223,070 on a Dairy Establishment:

The “establishment” featured large water tanks in the ceiling which allowed operator to pull a chain and flush the cow “exhaust” from the facility, eliminating the unpleasant task of shoveling the “exhaust.”

The invention was implemented with success, and the patent owners tried enforcing the patent, but when the case reached the Supreme Court in 1976 (Sakraida v. Ag Pro, Inc., 425 U.S. 273 (1976)) the Supreme Court held the patent invalid as obvious from the Legendary Labors of Hercules — invalidating the patent on the basis of fictional prior art!

For those who don’t recall the legend, the King Augeas owned more than 3000 cattle which he housed in an enormous cattle stable. The stable had not been cleaned in more than 30 years. Enter Hercules, who told Augeas that he would clean the Augean Stables in one day if the king of Elis would give him a tenth of the cattle. Augeas agreed to Heracles’ terms.
 
When Hercules arrived at the stables, he knocked a hole into the side of the stables, and then set about diverting the rivers Alpheus and Peneus, so that they would flow through this hole. When completed, the water of these two rivers flowed through the Augean Stables, carrying all of the accumulated waste with it.

It didn’t work out for Hercules, however, because the King reneged on the deal and banished him. Neither did it work out for Ag Pro, whose patent was declared invalid. Not all good ideas pay off for their inventors.