<p>Posting my own, rephrased and more general, question helped: <a href="https://stats.stackexchange.com/questions/222179/how-to-know-that-your-machine-learning-problem-is-hopeless">How to know that your machine learning problem is hopeless?</a>. In the end my question received pretty big interest, number of up-votes and one very good answer. As a side effect, the initial question that I was referring to attracted much greater attention. So this case shows that posting my own question as <em>@Glen_b</em> suggested, was a good way to go.</p>
