Stack Overflow has got an **[interesting feature](http://meta.stackoverflow.com/a/288387/839601 "find more detailed description here")** that may be related.

I can't tell that it helps to lower amount of bad questions _asked_ (I honestly don't know if this is possible at all) - but it _at least_ helps to save site home page from being polluted by such questions (bold font in below quote is mine):

> 
*All* questions flagged Very Low Quality now immediately enter [Triage](http://meta.programmers.stackexchange.com/q/7053/31260)
> 
...and **while these questions are being triaged, they're *not* shown on the home page. Take *that*, [wall of crap.](http://meta.stackoverflow.com/questions/258699/the-stack-overflow-homepage-is-over-emphasizing-bad-questions-and-a-proposed-so)**
> 
[![](https://i.sstatic.net/1rTGm.png)](http://meta.stackoverflow.com/questions/278380/help-us-test-question-triage)

See also:

* MSE discussion of instilling above features network wide:  
 [Triage and Help & Improvement review queues at sites other than Stack Overflow?](http://meta.stackexchange.com/q/251737/165773)