Give examples or samples of rendered images and people will guess at what library is used (also feel free to give example of when you've been surprside before ie. something really sounded like a real orchestra but was just fancy use of soundonts etc.) The point is to test the validity of claims that one library is vastly superior to another after mixdown. I really don't know the answer and am dying to find out if the hype between libraries is legit. My theory is that a person doing the heavy editing of a midi score and tweaking everything just right can make even a bad library sound good and vice versa.
!!! IF YOU ARE A LIBRARY SALESPERSON/CREATOR, please decline to post out of fairness to those wanting to keep things unbiased.