I am all in with the "sloppy" comment trying to anger the perp. Whoever did this wants to think they have mad skills to get away with it.Wild guess, but I think that LE is putting that out to prod the killer into a response. Icbw, but I described my theory in my first post on ws.
Editing to add my total conjecture:
Four people-that's brazen, that's a big calling card. Maybe that’s why LE (via the families, etc.) used the “made a mess” statement to bait him, hoping he'd respond. He’ll love all of the focus, but maybe irked by that “sloppy” remark, because (his thinking) if he’s so sloppy, why no footprints in and out? Why wasn’t there blood on the doors? How did he murder four people so easily and leave no obvious signs for the two he left alive?
this is wild guess on my part, but LE has gone through all of the predictable potential suspects and nothing, so maybe they, like I, think they're dealing with something different here. 2 FBI BAUs says something to me.