From Zelda Wiki, the Zelda encyclopedia
Scents are represented by invisible clouds of colored smoke and can be found in two Legend of Zelda games. They are undetectable by normal humans, and can only be seen with finely tuned senses.
In Majora's Mask, the Mushroom Scent is found in the Southern Swamp region. It can only be seen with the use of the Mask of Scents, and can be used to locate the Mushroom which can be put inside an Empty Bottle. The mushroom can then be taken to Kotake in the Magic Hags' Potion Shop in order for her to make Blue Potion.
In Twilight Princess, scents are much more important than in Majora's Mask. These scents can only be learned by Link while in wolf form. Link, even in human form, can pick up a visual cue that a scent can be learned by a colored cloud around the scented item. There are five different scents in the game, each one represented by a different color. However, Wolf Link can only remember one scent at a time. The old scents are not needed later. The first three scents (Children's, Illia's, and Poe's) cannot be relearned since the things that give them off (Talo's wooden sword, Illia's bag, and the Poe's body) disappear. The last two, however, may be relearned and used interchangeably; for the Reekfish Scent, Link can merely catch another Reekfish in Zora's Domain, and for the Medicine Scent, he can go into Wolf form inside the doctor's office (the doctor doesn't even notice him), move aside the crate that covers the puddle of medicine, and retrieve the scent. Scents are only visible while using the wolf form's heightened senses, which restricts Wolf Link's peripheral and distance vision and can be interrupted by taking damage. This can make it tricky to follow scents in enemy-infested areas. Losing the trail can mean backtracking until Link can find it again, because the smokey trail is only detectable a short distance ahead of Link.
The Youths' Scent (the scent of Talo, Malo, Beth, and Colin from Ordon Village) is the first scent learned in the game. It is learned in the Eldin Province of Hyrule while it is covered in Twilight. Its color is yellow, and the scent is picked up from Talo's Wooden Sword, dropped when they were seized by Bulblins. The scent leads Link into Kakariko Village, where he finds the kids along with Renado, Luda, and Barnes, hiding from the Shadow Beasts and Shadow Insects.
Scent of Ilia
The Scent of Ilia is the second scent in the game and replaces the Youth's Scent. It is learned in the Lanayru Province of North Hyrule while it is covered in Twilight. Its color is pink, and the scent is picked up from Ilia's purse. The scent leads Link along a winding path through Hyrule Hyrule Castle Town and into Telma's Bar, where he finds Telma and an amnesiac Ilia with a sick Zora, Prince Ralis.
The Poe Scent is the third scent in the game and replaces the Scent of Ilia. It is learned in the Arbiter's Grounds, the fourth dungeon. Its color is purple, and the scent is picked up from the cloak of a dead Poe. The scent is used to track down the other three large Poes within the dungeon, as well as help solve certain puzzles.
The Reekfish Scent is the fourth scent in the game and replaces the Poe Scent. It is learned in Zora's Domain near the Mother-and-Child Rocks. Its color is red, and the scent is picked up from a live Reekfish after fishing for one. The scent is used to track down the Reekfish that Yeto is taking to his wife, and also used to correctly navigate the Snowpeak base without getting lost in the blizzard. Unfortunately, the huge and powerful Yeti can take a more direct route than Link is capable of following, so Link will need to find the trail again after a few detours. Link finally catches up with Yeto at the beginning of the Snowboard Race at Snowpeak Top.
The Medicine Scent is the fifth and final scent in the game and replaces the Reekfish Scent. It is learned in the Castle Town Medical Clinic after Link gives Borville the Invoice. Its color is green, and is picked up by a puddle of spilled medicine in the Clinic. The scent is used to find the Wooden Statue, which had gotten some medicine on it while it was in the doctor's possession. The scent first leads Link to Telma's cat Louise, whom claims that the statue was stolen by a pack of Stalhounds. Link must defeat the Stalhound pack to recover the statue and help Ilia recover her memory.