In the early days of TeX.SE, [the same question came up][1], and I think [Andrew Stacey's answer][2] is a good one: 

 

>  1. Only ask the question if when reading it you think, "Hmm, I'd like
>     to know the answer to that one too.". 
>  2. Only ask the question if it hasn't been satisfactorily answered.
>  3. Re-ask the question rather than just cut-and-pasting it. 
>  4. Link back to the original question.

  [1]: https://tex.meta.stackexchange.com/questions/1/importing-questions-from-so
  [2]: https://tex.meta.stackexchange.com/a/47/103