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.
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 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 . 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?