Title, If there's a scent it should be always be visible if tracking is toggled on, but trying to collect one with insufficient Perception*Exploration should result in something along the lines of "your tracking skills are insufficient to get a clue of this scent."
Root problem this suggestion is addressing: Over the recent year or two, there has been like a dozen bug reports about stuff disappearing that could be explained by someone having bashed said stuff, but because the owner of the stuff can't see any scents, they rightfully assume it may have been a bug. Recent example.