How to close/answer a question based on a mistake?

Question

As a general, how should one answer questions that are based on printing mistakes?

E.g. Questions like this - should they be:

• Answered: Your Siddur is wrong. How would one prove this? How much research should one provide to prove one's case?
• Deleted: What reason would one give?
• Left unanswered with the comments explaining the problem? (Like this example has.) This wastes a lot of time when looking for unanswered questions to answer.

Sort of related to this question, but I'm not sure my question has the same answer.

Answer 1

I think that an answer that demonstrates, however it can, that a basis of the question is incorrect, would be valuable to the asker and anyone with the same false premise and is therefore the ideal response, within our Q&A model.