Question

A good research question should always be

Answer 1

It should not be controversial: it would only make the research less  reliable since people would have their opinions about the topic that they would want to defend.  It should also not be obscure: then it's hard to check.

The best answer is that it should be multifaceted: it should include a number of aspects, not just one, so that the test can check for those aspects, not just one.