Fig.: a person or thing that is doomed to fail

I decided not to take up a partnership with John because, so far, he has failed in every business that he has gone into. In fact, he's a dead duck

Ho deciso di non mettermi in società con Giovanni perché è un cavallo perdente; infatti, tutte le attività che ha intrapreso sono fallite

The expression is actually a shortened version of an old pioneer saying: never waste powder on a dead duck. From that advice the term "dead duck" came to represent anything that is done in or played out