I'd say that there just needs to be some reason to think that there is genuinely more than one answer to the question. For instance I could as "is the moon made of green cheese?". Now clearly some people have said that the moon is made of green cheese (as a fanciful belief), so it is a claim that has been made, but it would be very silly indeed to have any genuine skepticism whether the moon is actually made out of green cheese. So I would say this is not an appropriate question for skeptcsSE.
In the specific case of the question that I suspect generated this question, it is possible that Robin Williams was murdered, rather than having committed suicide, but is there any evidence to suggest that his death is anything other than suicide? I'd say "no", the sheriff's report says nothing that casts any doubt on the question, and the only reason they don't give it as the official cause of death is that there is a protocol to be adhered to. The question gave no reason to suggest it was anything other than suicide and the TMZ report did not claim that this was the official cause of death. So where is the substance?
How could this question be answered to say "no Robin Williams did not die from suicide" what references could we give to cast doubt on the current view that it was suicide?