Many questions seem to be concerned with certain things being more or less 'healthy'. This seems very vague to me. What does healthy mean? Should we require people to clarify a particular metric (such as mortality)? I'd say yes to this - healthy is a very vague word, and I am very strongly on the side of becoming a site that deals with issues rigorously (see skeptics.SE).
A few questions that use the term:
I don't think there generally needs to be a "requirement." It's all about context. If the question is answerable in the context it is asked, you should answer it.
You can usually infer the level of interest and specificity a person needs based on what they are asking. If a layperson wants to know if/why natural sugars are more healthy than refined, there's really no need to harangue them into specifying dyslipidemia, HDL, or general loss of adipose tissue. People asking the broader, vaguer questions are generally laypeople, so it is perfectly acceptable to answer their questions in that context.
I think it’s not so much an issue of rigor as it is breadth. All of the questions you give as examples seem to me to be fairly clear: «Are there any adverse health effects associated with X?» Such questions are fairly broad and open-ended, and in some instances would probably be inappropriately so. («Is smoking unhealthy?») On the other hand, «Is natural sugar healthier than refined sugar?» is simply asking for information about what aspects of one option might be more or less salubrious than the other. The answerer is left to supply the details based on an understanding of the relevant available data. This is a sensible way to ask a question.
This sort of question is not Skeptics.SE style: «Evaluate this claim.» It is, however, a reasonable Q&A style: «Help me understand this.»
