If he's a dud, you won't recoup the money. Lots of your signings have not worked and the players have lost value. You will end up with players on long contracts you can't get rid of, or sell them at cut price to United and other poorly managed clubs.
If he's a dud, he's a dud but there are different levels of dud. Werner for me was a dud (considering how much we paid for him) but a good kind of dud (as in he showed he could still contribute despite struggling in front of goal), despite being on nearly £300K a week. Took a hit on the transfer fee, sold him for half of what we paid but we got out of being on the hook for £300K a week for another 3 years, which is what he had left on his deal.