I asked a similar question recently, which was closed as an exact duplicate. I got redirected here, and to one other question.
The best of the answers that I've read give me these hints:
The issue is not so much one of subjectivity, but of answerability. A good question is one that encourages a good answer. Maybe more than one good answer. Questions that are worded wrong can be hard to answer.
The Programmer's area seems to focus more on conceptual questions than SO does. I'm going to spend more time over there, to see if design questions get different treatment over there. I wonder how newbie askers get redirected over there.
Answers to design questions can direct people to where they can read up on design techniques instead of outlining the technique. Example: There's a certain class of questions about SQL table design where directing them to the "Class Table Inheritance" tag works well, judging by the responses.
i have learned to stay away from questions that the asker thinks is technical, but I think is one of design. Many questions of this ilk are rat-holes.