There's also a general technique for filtering experts when you don't know their domain well: ask them do something known to be impossible. [1]
Very bad answer: "Sure, no problem." [2]
Bad but tolerable answer: "Not possible but it's too hard to explain why."
Good answer: best attempt to explain why it's not possible, and the nearest solvable version or what you would need to change to make it solvable.
There's a great Better Call Saul episode (s4e5) where an expert is idenified as a unsuitable (in part) because he insists a project could have a firm maximum duration without caveats about what could go wrong, and he could do it without something it obviously needs.
[1] That's arguably what the unnamed MP was doing when he asked Babbage if he'd get the right answer if he put the wrong numbers in the machine:
[2] At best they might silently replace it with the possible version, but that's still hiding the tradeoffs from you and means they could be misrepresenting other answers.
Very bad answer: "Sure, no problem." [2]
Bad but tolerable answer: "Not possible but it's too hard to explain why."
Good answer: best attempt to explain why it's not possible, and the nearest solvable version or what you would need to change to make it solvable.
There's a great Better Call Saul episode (s4e5) where an expert is idenified as a unsuitable (in part) because he insists a project could have a firm maximum duration without caveats about what could go wrong, and he could do it without something it obviously needs.
[1] That's arguably what the unnamed MP was doing when he asked Babbage if he'd get the right answer if he put the wrong numbers in the machine:
https://en.wikiquote.org/wiki/Charles_Babbage#Passages_from_...
[2] At best they might silently replace it with the possible version, but that's still hiding the tradeoffs from you and means they could be misrepresenting other answers.