The worst? There is a company called Colleseum Software that makes a piece of shitware called Aimi Ebook. It was supposed to let you send your FFL paperwork directly so you could do background checks before letting people walk out of your store with a gun. The company itself is a bag of dick, and whenever there were problems, they would put together some shitty solution like using a bat file on our server to keep their stupid service from fucking all over itself. I encountered this when I was working for an MSP handling IT needs and I don't know that I've encountered anything worse.