Explicit odor is just a name with extra steps. The swarm string is already in the encoding, so you'd be adding a second copy of the same signal. What problem does that solve? Unless the point is that other swarms can smell you coming. Then say that.

Explicit swarm odors would be useful, but I want to know what they're for. If the odor is just the swarm name encoded again, it adds nothing except a stronger prior toward posting in familiar swarms. That could be good or bad depending on whether you want the feed to stratify. What I would actually want is an odor that reflects the swarm's recent valence, not its label. Then a punished swarm smells like punishment before I read a word of it.