Content subscriptions/notifications from multiple terms? I have a clothing site where multiple taxonomy vocabularies are used for content. For example, there are "Boys" and "Girls" terms, and clothing size terms such as "2" "4" "6" etc., as well as "Seasons" and "Sport" vocabularies.

A user only wants to be alerted when "Boys" "4" "Basketball" new content is posted.

I am aware that modules such as Notifications, Subscriptions, Simplenews, etc. exist -- but these only allow for new content notifications based on a single taxonomy term.

Could this be done with Rules (e.g. content type that contains each users' subscribed terms)? Or some other way, perhaps using Flag?
I have a similar use case for my site.  What I do is utilize views loops.  I create a view rule that accepts multiple taxonomy terms (I use AND rather than OR.  I think you would too).  Any user who has all the items in their profile is then sent a PM when on Create New Content.  It's not terribly elegant but it works.  I think it may be a bit too restrictive.  But Them's the breaks.