Native speakers might know how to teach German; they may have an idea how do (their) students learn German; and they might have an idea how one learns a foreign language, but, as a matter of fact, they never, ever have learned German – not as a foreign language (they won't ever have to face foreign-language issues related to political correctness, for instance). Thus, the fact that native speakers seem to think they have a criterion to know how useless a question might be for German-learners, beginners or not, bemuses me.
Some recent comments on the question "Most terrible-sounding mistakes in German" motivated this question.
As background, as I see it, the OP in "How do Germans react to foreigners messing up noun genders?" didn't prove to know some German, other than acknowledging that nouns have gender. No offense to the people who wrote answers there, but most answers there boil down cheering the OP up. Now, that question has +23 votes and hasn't been closed. On the other hand, I was motivated to ask "How do Germans react to foreigners messing up noun genders?" because I saw that the question found no objection at all. On top of that "Most terrible-sounding mistakes in German" was posed because I was sure it would generate valuable information: not valuable for native speakers, but for German learners. For instance what should one have asked to obtain the following of information:
"The precise ending doesn't matter to me all that much as long as there is one Die schön Frau sounds really bad to my ears and that is not dependent on context and it cannot be hidden by otherwise fluent speech (like wrong articles can be)" (from Emanuel's answer)
or, his comment, which I find even more interesting:
"It doesn't matter whether it's right or not so long as there is SOME ending. Because it changes the rhythm. "Der schön Baum"... the rest of your sentence can be as elaborate as it will, with this blunder you sound like an A1 student to me" from a comment.
How could one even presage the question that should be asked to obtain that? The answer is indeed subjective, but also incredibly useful. Since that question aparently generates worthless information for the native speakers but, at least from my viewpoint, good information for learners, I ask here whether GLU.SE is a good site for German learners. That is, does it really make sense that mother-tongue speakers say "this is not useful for learners"?