[HockeyIlliterate]

At this point, I don't see any value in clearing anything with your wife. If she isn't willing to confront the slobs over it, then you will have to do so.

To that end, box everything up, trash and all, and throw some of your own half-full bottles of coke in the mix, and then go over to their house and dump it all out on their lawn. Throw some of the clothes in the trees too for good measure. The higher the better. Then spray it all down with water. I'd recommend doing it all at night for the reason noted in the ETA below.

And then forget about it and them.

ETA: If looking for a bit of extra revenge, put a yard sale ad up on Kijji or wherever, scheduled for the morning after you drop off all of the clothes and junk in the yard. Nothing brings out the best in humanity like people scavenging through random wet junk in someone's yard.