I know Prime Hidden in Plain Site is already a topic for a few different discussions, but I have another interesting question regarding it. Is hiding rules for acceptable answers in spoiler tags appropriate or acceptable? I feel that answers should be considered valid if they meet all the visible requirements of the given question.
In dialogue back and forth between AE and BmyGuest on this answer BmyGuest states that the answer is wrong because of a rule that is hidden in a spoiler tag. Is this something that should be allowed in questions?
Don't get me wrong, I thought the question was unique and intriguing, but the way it was presented left some question that probably should be answered...