Going by the answer from @Bobo, I think that the very definition of what a lifehack is, is actually a solution, not a question.

So we need to try and flip it around and think what sort of questions produce lifehack solutions. Looking at [this list of top lifehacks][1], these are the questions that would have to have been asked first to receive these sorts of responses:

 - How to find your luggage on an airport carousel
 - How to keep a door from latching, without wedging it open
 - How to properly iron around the buttons of a shirt
 - How to prevent bin bags from leaking
 - How to keep dirty laundry from smelling whilst travelling
 - How to fill a container that doesn't fit in the sink
 - How to stop charger cables from breaking
 
They all seem to revolve around life's little annoyances, so maybe that's what the question scope should be? True, not all of them are going to produce lifehack answers, but in a Q&A format, these are the questions that are most likely to do that.

I think that my definition for the question scope would have to be something along these lines:

> "Questions are in scope if they request a solution to a problem, that the majority of people face at some point in their life, that can be
> implemented more quickly, with more common tools, and is easier or cheaper
> than common or obvious methods, if those methods already exist. 
> 
> If a question already has a common solution that they want to improve,
> they must explicitly state the method they want an improvement to, and
> which aspects needs to be improved"

In my opinion, this scope will allow all of the questions above, and all of the questions currently on the site that aren't already on hold, with some editing. When I say editing, the only thing that would need to change for the majority of cases that don't match the scope, is to add how they would like to improve upon existing methods. For example, https://lifehacks.stackexchange.com/questions/236/how-do-i-prevent-ants-and-cockroaches-from-getting-to-my-food could clarify how they would like the solution to be better than the common solution of pesticides, ie cheaper, more effective or using items around the house. OPs own answer in this example used cucumbers, so if that was the result they were wanting, they would ask for an answer using objects that are normally easily obtainable or already in the house

As for who our experts are, that's a whole other debate. But I do see people on Facebook have graduated from somewhere called "The University of Life", that sounds like a good place to start asking ;)


  [1]: http://www.lifehack.org/articles/lifestyle/100-life-hacks-that-make-life-easier.html