While I was working as school psychologist, I came across parents who would often complain about the performance of their ward, which was never upto "their expectation". Well I do appreciate parents having a positive attitude towards improving upon it, but sometimes they are unreasonable.
My teachers would often say "all have been gifted with same brains" i would disagree. I beleive, neither does each have the same gray matter, nor equal oppurtunities. Besides this, the feedback of parents is of great value to the child, positive criticism will always be taken as a motivator. Sometimes parents would forget that unconditional love is something a child should never be deprived of. Acceptance suddenly turns into rejection seeing the report card!
I have faced it, and have felt bad about it. But I just forget the hurt, when my sister would tell me, "we know you can do better if you stop being complacent".