Now you guys probably know the XY problem (asking the wrong question X to when you really want to solve the problem Y). The YX problem, on the other hand, goes like this:
User: "Hi, how do I do Y?"
SO: "Why do you want to do Y?"
User: "Because I want to do [use case]"
SO: "Are you sure you don't want to do X instead?"
User: "No I don't, I have this constraint and this use case so I'm pretty sure this isn't about X and I really want to do Y."
SO: "Are you sure this isn't a duplicate of [some question involving X]?"
User: "No it's not, the question while similar doesn't have the same constraint or usecase and I have searched SO for a while for questions that specifically involved these and didn't find any so I really need to do Y."
SO: "Wow, I can't possibly imagine why you, for a use case you've examined for a while and which I have been made aware of five minutes ago, could possibly want to do Y while not doing X. I don't know and I rest my case. A solution to Y probably doesn't exist anyway."
Answerer: "Hi to do Y you have to do this [hacky snippet]" (answer accepted)
User: "Cool, thanks!"
SO: "This is bad practice and I don't condone it. It shouldn't be upvoted or the accepted answer."
--------
Of course this is the optimistic scenario, where the question does get eventually answered.