I don't care about an answer key being wrong - typographical errors are a fact of life, and as long as they're not too common that's fine. What I care about is teachers using an <i>answer key</i>. I never <i>heard</i> of such a thing until I came to the United States. At least in Ireland, where I grew up, teachers are expected to be good enough at the subject they teach to do the damn homework assignments. There are no such things as answer keys for textbook problems.<p>Every time I bring this up with an American teacher they go into this long litany of how busy they are and how poorly they're paid and so on. I don't give a fuck. If you are using an answer key, you are No Good and I don't take you seriously. I refuse to give a fuck about any of your other problems if your brain is not minimally engaged with the subject material in which you purport to be competent.
I disagree with her premise. Higher stakes tests presumably have their answer keys reviewed more closely. Multiplication problems in math textbooks appropriately don't have their answer keys reviewed with the same degree of scrutiny. In medical qualification exams, if enough people get an answer wrong, it may be reviewed for an incorrect answer key, or even thrown out for being confusing or ambiguous.