The problem is that most parents aren't informed enough to even know to question an interpreter's qualifications. They might observe a class and see the interpreter's hands moving quickly and smoothly and think, "Wow, she's really good," then they'll look at their son who is watching the interpreter attentively and occasionally nodding, and they'll think everything is fine. Little do they know that the interpreter was not using conceptually accurate signs, and because she was overwhelmed by the speed at which the teacher was talking, she was quickly summarizing and leaving out a great deal of crucial information. At the next IEP meeting, the parents praise the skill of the interpreter and then turn to the matter of trying to figure why their son just doesn't seem to be performing at the same level as his peers.