I believe the way this has been worded in the past is that questions ought to "start from a text." In this flowchart, I worded this question as "Does your question arise from and focus on the text (and not primarily on those things to which the text applies)?" It also asks, "Does your question include and/or properly cite the Biblical text(s) of relevance?"
My understanding is that it's OK to ask about theoretical aspects of hermeneutics itself, but if asking about the text, you must ask about a specific text. Otherwise these questions tend to be fishing expeditions that begin from some abstract idea or doctrine rather than from the text (e.g., "I think this [idea]. Can you prove me right [or wrong] from the Bible?"). Alternatively, it could be someone who did not perform minimal research (e.g., "My mom told me that Jesus said [X], did he / where is this?").