I'm enormously happy and relieved to report there were no incidences of this problem the entire summer of 2016 (after a constant barrage of them in 2015). I don't know whether the perpatrators moved or were shut down by their landlord; I'm just so glad it was a problem we did not have. So I will be closing this issue at long last.

Problem apparently resolved.

I live on that block, and I too am relieved that the hosts have moved away. I do, however, feel sorry for whoever their new neighbors are...