As usual, it is "Buyer beware."  Not-all dogs make it successfully through the program, for various reasons, but I think, if a company has invested the time and money it takes to train one, it is going to pawn that animal off on someone.  This is a generalization, however.  I'm sure there are some companies that have ethics.

There is a deaf, dumb and disabled woman in our neighborhood, and she recently acquired a "service" dog, along with a scooter.  From what I see, this dog is of not-much benefit.  It's too small for its purpose, barks all the time, is too energetic, and always wants to run and pull on its leash.  The poor woman looks miffed all the time.