I have been very reluctant to give away indiegala keys for quite some time now as they seem to be involved in a lot of key invalidation. But as most of the time only unused keys get invalidated, I finally figured that I should give them away as long as they might work. I didn't have many failed GAs from doing this the last couple of months, but a few.
That said: If a key doesn't work, I won't provide replacement. I will be happy if you agree to delete the GA in that case, but if you don't you can always mark as not received.