Detecting Creatures with Scent

Question

My druid has the Wild Shape Focus spell, and one ability that it grants (via pest form) is "imprecise scent 30 ft." I read through the relevant rules, and I'm not sure when this ability would be useful.

Imprecise Senses:

Hearing is an imprecise sense-- it cannot detect the full range of detail that a precise sense can. You can usually sense a creature automatically with an imprecise sense, but it has the hidden condition instead of the observed condition. It might be undetected by you if it's using Stealth or is in an environment that distorts the sense, such as a noisy room in the case of hearing. In those cases, you have to use the Seek basic action to detect the creature. At best, an imprecise sense can be used to make an undetected creature (or one you didn't even know was there) merely hidden-- it can't make the creature observed.

Scent:

Scent involves sensing creatures or objects by smell, and is usually a vague sense. The range is listed in the ability, and it functions only if the creature or object being detected emits an aroma (for instance, incorporeal creatures usually do not exude an aroma).

Most creatures can hear ^{[citation needed]}. It seems like the only advantage to having scent is that, in the unlikely scenario that someone is hiding from you in a noisy room, you have a second imprecise ability you can use to sense them-- but common sense holds that, while you can try to hide your noise pretty easily, you cannot hope to hide your scent without specific gear or magical assistance. Is there any rules difference between hiding from a creature with scent and hiding from a creature with hearing?

Answer 1

Scent allows you to detect enemies trying to sneak up on you in more cases than hearing would.

Because most creatures have hearing (Pathfinder seems to assume all creatures do unless they say otherwise) many creatures will attempt to move quietly by using Stealth.

Scent bypasses these attempts to Stealth (allowing you to become Aware of them) unless they've taken measures to block your Scent from working. A creature that knows you(r form) has Scent may do so, but many other creature either won't know that or simply don't have the means to mask their scent.

Notably, Scent is typically a vague sense meaning

At best, a vague sense can be used to detect the presence of an unnoticed creature, making it undetected.

Whereas upgrading this to imprecise allows

You can usually sense a creature automatically with an imprecise sense, but it has the hidden condition instead of the observed condition. It might be undetected...

Mechanically, this bypasses Undetected; Unnoticed is the more extreme version of Undetected that would allow creatures to really take advantage of you (potentially as dangerous assassination attempts with future content releases), while Undetected is nearly as bad.

Unnoticed
If you are unnoticed by a creature, that creature has no idea you are present at all. When you’re unnoticed, you’re also undetected by the creature. This condition matters for abilities that can be used only against targets totally unaware of your presence.

Undetected
When you are undetected by a creature, that creature cannot see you at all, has no idea what space you occupy, and can’t target you, though you still can be affected by abilities that target an area...

Hidden
While you’re hidden from a creature, that creature knows the space you’re in but can’t tell precisely where you are... A creature you’re hidden from is flat-footed to you, and it must succeed at a DC 11 flat check when targeting you with an attack, spell, or other effect or it fails affect you.

Notably, any one ally reducing a foe to Hidden allows everyone to treat them as Hidden because you effectively know which space the target occupies. Being the one with Scent gives you and edge for allowing your party to counter an ambush.

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A note on hiding from Scent.

There does seem to be allowance in the sidebar on p465 implies that you can generally attempt to hide from senses, including Scent, with appropriate narration (perhaps covering yourself in mud, etc); however, the Foil Sense Skill Feat allows creatures to defeat Scent without specifically preparing for it. Fortunately it requires Master in Stealth, so few creatures will be running around with that capability.

The Stealth skill is designed to use Hide for avoiding visual detection and Avoid Notice and Sneak to avoid being both seen and heard. For many special senses, a player can describe how they’re avoiding detection by that special sense and use the most applicable Stealth action. For instance, a creature stepping lightly to avoid being detected via tremorsense would be using Sneak.

Based on this, some GM's (myself included) would instead call for a Disguise or Survival roll instead, if covering yourself with mud to overcome your smell was the task at hand.