Used Uselessly

Riddle: When I'm used, I'm useless, once offered, soon rejected. In desperation oft expressed, the intended not protected. What am I?

Answer: A poor alibi or excuse. Source: https://www.riddles.com/index.php/803

When I'm used, I'm useless, once offered, soon rejected. In desperation oft expressed, the intended not protected.
What am I? — Used Uselessly by Anonymous Riddle