I found these questions on meta.SO: 

 * http://meta.stackexchange.com/questions/91086/where-can-you-discuss-or-ask-for-comments-on-a-data-explorer-query
 * http://meta.stackexchange.com/questions/107137/where-do-i-ask-questions-about-data-explorer

Based on the answers provided there, it seems that [meta.SO](http://meta.stackoverflow.com/) is the place for asking questions like that and that ([data-explorer](http://meta.stackexchange.com/questions/tagged/data-explorer)) is recommended tag for such questions.