Just took the AFAST...scored a 145....definitely a good idea to read through a couple of practice tests beforehand. If you don't have any helicopter knowledge you may really screw yourself by not reviewing.
The usual cyclic/collective questions and other helo questions are things that you wouldn't know without studying. As well as flapping, coning, dissymetry etc...
Other guy in my test appeared to not have prepared very well, I don't believe he did very well. (actually I know he didn't). He had a few fixed wing ratings, probably just out of flight school. But I got the impression he thought he knew more than he really did. Plus he was telling me how bored he was with fixed wing a/c. I never bothered to tell him I've been in jets the past 10 years. So if he's bored with fixed wing having only flown a few hundered hours, he may need to find a new career.