There's a highly upvoted question about discerning maintainable code from unmaintainable code: How would you know if you've written readable and easily maintainable code?. It's a community wiki, and it seems that some effort has gone into trying to improve it: How would you clean up a question asking if you've written readable and easily maintainable code?.
But my first reaction to this question is that it seems like a poster child of the "Too Broad" close reason. Literally entire books and volumes and fields of study have been devoted to this topic. It's also an ever changing target as languages evolve, and some practices that are good in one language are horrible in another just due to the limitations and differences. It also makes a remarkably poor dupe target for any question that asks about a specific issue, as it offers no helpful advice for a particular case even when it's appropriate to provide a more specific answer.
I'm hesitant to flag it since it seems like it's been discussed before and high reputation users are aware of it. So before I go flagging it or asking for closure, I'm posing the question of whether my evaluation is correct. Is this question Too Broad? Why or why not?