The blackcoin developer should fixed the bug and help finding missing coins. Fuking BC dev should care community!!!!!!!!!!!!!111
If it is BCs dev fault, why none of the other exchanges are affected?
This turns out to be same thing as MTGox, another bug, but only with impact if your implementation in an exchange is very unusual, not to say faulty.
Basically, if they trusted the wallet, which is something everyone does when they use a wallet. To what degree... well that depends on the implementation.
The timing of the events tends to make a difference as well.