I have answered many questions and the question asker does not reply or mark as answered. These questions are bad for the site and will make it have more unanswered questions.
Is there anything we could do about this
Usually the correct process would be to post a close flag under "unclear what you're asking". If you need a reply to answer the question this is correct anyway, if not, then others users may upvote your answer (any upvoted answer stops the question being marked as unanswered).