Measured Against Reality has a post on meaningless questions, questions that are unanswerable because they are poorly formed. Like 'What is outside of the universe?'.
He uses a lot of examples from the debate over evolution and the big bang. When people disagree on a complex subject, they often challenge the other side with questions. They find something that the theory doesn't seem to explain. Sometimes it's a good challenge, sometimes it has an answer, and sometimes it's gibberish.
The problem is that such questions don't have a place in rational discourse, at all.
When you make an argument, you start with premises, follow a logical pattern, and reach a conclusion. If your premises are true and your logic valid, then your conclusion must be true.
For someone to attack your claim, they should make an argument that one or more of your premises are false, or that your logic is invalid. Their argument should also have premises and logic, and be subject to the same style of attack.
Challenge questions sidestep all that. They attack a conclusion without attacking the premises or logic that lead up to it. They make an argument, but make it difficult to criticize by obscuring its implied premises, which may be gibberish. It is this easy and hard to counter attack that makes them popular rhetoric, but bad argument.
Questions for clarification or knowledge are fine. I am only against questions used to attack structured arguments.
We should not ask 'Well then who did Cain marry?'. It provides no premises, and disproves nothing. We should make assertions about who would have been available for Cain, and those assertions can be rationally discussed.
Conversely, we should not answer challenge questions, whether they are meaningful or not. We should put it upon the challenger to make a good argument against our premises or logic. We have no obligation to be sniped at, and if our arguments are good, then theirs will fall flat.