I am writing this with my own banned question in mind.
As a suggestion for ban policy:
When a mod decides to ban certain questions which are related to the field or expertise of your site but for some reason or another are not welcome, they should do it constructively. Which means, they should direct the person to a different site where they are more likely to get help with their question. If no such site exists or is not known, then your site is the best shot the person has, and banning the question is not productive. You might not like the question and it might end up not getting any answers at all. Let the community decide what to do with it. Excluding it a priory is not fair without suggesting alternative ways to get help.
What do you think?