one year to put in place, check this out..
"every" child has a smart phone now, this obviously must be in, or near real-time.. a child could visit a house, then quickly post what candy he received.. "I got a full-size Musketeer bar at 236 Jones street"! or, "damn, forget 339 Henslee, they are giving out stale lollipops"!
he can even mention displays... "hey, 561 Thacker has a cool dungeon, a Mummy raises up and scares the crap out of you!"
it can work from both sides.. a Homeowner could post an alert.. "that little Bastard who posted about my giving stale lollipops is a Jackass.. I just bought those at Walgren's last Thursday!"
oh, the possibilities..