Idiom
be a dead loss
1.
if something or someone is a dead loss, they disappoint you because they are of bad quality or because they are not able to do what you want them to do.
The meeting was a dead loss. We didn't come to a single decision.He may have been a great poet, but he was a dead loss as a husband.
2.
to be very bad at a particular activity or subject.
I was an absolute dead loss at sport when I was at school.
(sometimes +
at)