@quagmire  I looked at the princeton review book. It breaks down the types of errors that you see on the test. There are like 7 or 8 major errors and others are just miscellaneous. But that just applies to the 400 to 500 difficulty level questions (my opinion). But for higher level difficulty questions MGMAT tests have a better approach to pinpoint the error and fix it. At that level either all the options seem right or all the options seem wrong.

@newlynew ( I dont know how much of it is true but here it is ......)
                  i heard that they send people to take the test not for getting into a uni but for memorizing the questions that they see on the real test and then sell the questions to others preparing for the test. Thus the term jjings or jungle juice
The pool is massive for the questions and the test adjusts the difficulty level as you go through the test...but even you see five or ten questions that you know then it will bump you up several difficulty levels and besides 5-10 questions are experimental questions on the test
they  also shut down a website named scoretop.com which gave real live  questions for a membership fee. But this was a couple of years back. The website was run by a chinese national. Now the website has a warning posted on its frontpage. Anyone who had a membership and now in colleges (top 25 mba programs, i bet they got in with a 700+ score) are under scrutiny.
     
After rigorous hunting expeditions on the almighty internet i came across some sets of questions commonly referred to as  sets. I was able to download about 60 or 70 sets. I think these are questions retired by them  because I have seen some of the questions on OG books.