Unless I am somehow physically dropping things as I move then I reject the actual bread-crumbs thing, it is however a great way to describe how smell trails actually work, they're just eency-weency molecular crumbs.
I, honestly, do not want smell in the game. I can't smell, and I don't want to smell, the world of 7DTD anyway, that actual world would be incredibly stinky in so many ways. Thing is there is no way to directly convey this sense out of our major 3. I can see when I play, and I can hear when I play, but I cannot smell, and I don't want to anyway.
If/when they do bring back a fuller smell system how in the hell do I gauge how stinky I am? Will there be a smell meter? Will I have to dig through menus once again to find out if I am stinky or not? That will seriously annoy me if it is poorly represented and hard to determine.
Regardless I'll accept whatever they do, but if I had a choice I would negate smell entirely, forever, unless they can somehow pull it off effectively.
I honestly want to be wrong. But this is a dev choice, in an evolving alpha, so I am down to try out whatever, and won't make any kind of final judgement until I have thoroughly played multiple games with the system in place. Just spitballing and debating.