Why? Even a really bad smelling person can't be smelled unless you're really close to them or in an enclosed space.
Back in the day, when I was serving in the 101st, we had some 45 day training missions, where IIRC, we got a chance to bathe at most once a week. All of us reeked, but at less than a football field length.
There are few things that a person can ingest in some way that can cause a smell at a large distance, but very little. On the other hand, zombies are kind of animal-like and seem to have the ability to smell things at a distance. That is pretty common in shows and books - either increase smell, increased hearing, or both. But just because they can smell stuff doesn't mean a person can. And I doubt most PVP players would want that and anyone not playing PVP doesn't have any use for that.
OK, now I have to put this out there.
I don't want to hurt folks feelings, but this whole 'smell' mechanic is just nuts.
Remember where I posted when I was on an extended field problem, with little to no chance to bathe? That was 100+ guys living in the field. Has anyone gone into an abandoned home, where an animal crawled in, died over the winter, and then rotted come spring/summer?
Now we are supposed to suspend our disbelief, and accept that a bunch of walking dead,
rotting human and animal corpses, can smell anything but their own putrefaction?
Naw dude naw.
What might be a good ingame use, would instead be, the surviving, living 4 legged predators, instead of the rotting dead, being able to smell us, the human survivors, and...