When a deadline had passed sent blank tapes to clients and then claimed the postal services had wiped them when scanning with xrays, asking the clients to send back the tapes so we bought a few more days
"I guess we'll have to send them another blank tape" was a common trick in the 90's.
This also happened more recently in the CD era with intentionally badly burned CDs.
I worked for a business that sold videos burned to very cheap blank DVDs, for a pretty high price. We tested them onsite, and had about a 20% failure rate (they cheaped out on the equipment, too) and the passing discs wouldn't work for about a third of customers anyway. I think those discs delaminate after a few years.
Even in the internet era. In high school I often just renamed some random file to a .doc extension and sent that in. No teacher ever had any idea. I'd just play dumb that I had a bad computer.