We've had failures, too. Those are always sad.
Do you rescue them, make them healthy and find homes for them or do you keep them?
I got a freaked out cat (mistreated product of divorce) and had to lock her up for a month before being able to touch her. All she got was good food, clean water and fresh litter; we didn't even try to touch her until she tried to touch us. After that she was a fantastic pet.
The ones you can't help are indeed sad. We took in another cat like that and her mind was too far gone. Poor thing.