What is the Tell?

There has to be a give away for Scratch to go from Tardust can abuse Lizzy any way he wants to do not touch her ever again. All I am left with is Smell. Her vomit gags Tardust and Bricks. Scratch does not seem to mind. Saul is not troubled by the barf bag. He simply says someone lost their lunch when he finds Lizzy's shoulder bag.

So, let's leverage smell. They break the first sweat vial or two and nothing happens. The crew jumps to the conclusion that it is not enough so they break all of them and tahdah, the zombies come. Like a good scientist Lizzy keeps the sweat separate, to see if the zombies are attracted to someone in particular. This information is lost when they break them all. Going back to the breaking of the first vial or to, maybe the zombies do not care about the first two people... It is not more is needed, it is they may only be interested in certain people.

More or a certain person. We cannot rule either out.

Where else can we leverage smell? It is probably nothing, but Saul tell Angel you smell worse than usual on the night of the war, right? At least i thnk it was Saul. Earlier that night a drunken Burt says, Angel is puking in the bathroom.

Going further back to when Lizzy figures out the car trap we find out they smell like shit. Probably nothing again, probably just simple hygiene in the Apocolypse, but I think Puck says you smell like shit Sarge, when they get to Irwin and doesn't he say something similar to Saul, Vic and Lizzy at the reunion at the colony at the end of Season 3? No love, you all stink any way or something like that