Now, the ONLY time I could EVER think of using a braindump for ANYTHING would be in the form of a lab manual - that is, take the question as written, toss out the answers, and model it up in a bench situation. At that point, it's a experiential lab. But, using the question from the exam, as study material undermines the idea of questioning someone's applicative knowledge.
See, if we look at this from a Blooms perspective, a question from a scenario that a candidate has never seen tests applicative knowledge. If the candidate has seen the question, it goes down to Understanding or just Knowlege levels - which is not meet for a certification that is testing applicative knowledge.
So one would hope that if they have modeled things in a lab situation, they've covered the points that might be addressed in a braindump question, anyway. I have seen very few GAS questions that have been so off the wall, as to be purposely evasive. Usually, either you know it or you don't.