Based on my experience, the suggested answers for most past year examination papers are quite reliable, MCQ answers to be specific. However, for open-ended questions, there are some doubt as to the accuracy of the suggested answers. If you encounter such cases, it would be good to check with your child’s tutor or school teacher for a more rounded answer. Of course, we are not teaching parents or our kids to be "wary" of the suggested answers. However, when in doubt, always ask. As for assessment books, I will look for those that has been reprinted more than once, but of course I will first "sample" a few questions and the books’ suggested answers before deciding on a good assessment book.Hope this helps.