Not yet finished rereading people, but after reviewing final vote counts of lynch bandwagons and other big bandwagons at their critical mass, I realized that:
+ HW was on pretty much all of them, except for Serela's and PX's D2 wagons.
+ BT came a close second with 1 less wagon jump if I counted right, and in his case he didn't hop on my and NNR's bandwagons.
+ Shadoweh didn't jump wagons as much, but it seems all wagons she jumped had scum on them one point or another. This includes the D1 IHNN wagon that also included PX, BT and Serela. It seems unlikely that scum!Shadoweh (and her scumbuddies) would (let her) jump on wagons with scum this much, and as I see it a PX/Serela/Shadoweh scumteam wouldn't have the skills and guts to use Shadoweh to mindscrew around this much, so I think Shadoweh isn't scum.
+ Actually for that matter, even if BT was scum instead it's still unlikely that he would agree to pile all scum votes on IHNN like that while the case against him wasn't solid
So with the possibility of all 3 scum being on IHNN wagon tentatively discarded, that leaves HW.
HW is now my prime suspect.