We really need to agree on this one early on. What do we do with questions who by nature are spoilers? I mean, not part of the question, but the entire question.
For instance, asking about a character who's identity is only revealed later in the manga (but not the anime). Even the question's title itself may contain major spoilers in that case.
The source of the problem comes from the unique relationship between manga and anime. The manga would always be ahead of the anime, and there would always be people only viewing one of the two.
Therefore, questions on topics entirely revealed on the manga is likely to produce heavy spoilers for viewers of the anime.
How do we deal with those? The only way I can think of is implement a feature to mark an entire question as spoilerish.