The typical guy probably has two or three bottles of fragrance in rotation, one of which he chooses each morning based on factors like what he's wearing or whether yesterday's market made him grumpy. But then there are the men who put more thought into how they smell than how they look, the ones who hunt down colognes the same way you might seek out limited-edition sneakers or small-batch bourbons. Their arsenals are roughly the size of a serious DVD collection. Chris Fisher, 39, a tech executive in the San Francisco Bay Area, owns 250 bottles. "My wife moans and groans that I can't walk out the door without fragrance on," says Fisher, who once flew to Rome specifically to visit the renowned Italian perfume shop Profumum. Tarun Bhatnagar, 27, who works in marketing in Baltimore, has been a scenthead since his dad bought him Polo Sport when he was 8. He now owns around 60 colognes, which he thinks of as a starter art collection. "I can't afford photos or paintings," he says.

Fragrance freaks don't wait for girls to give them new scents as gifts; they make sacrifices for them. Paasha Motamedi, 19, a student at New York University who's gone through eight bottles of the spicy Chanel Platinum Égoïste in the past six years, canceled several dinner dates last November because he'd decided to spend $200 on 3.4 ounces of Le Labo's grapefruit-and-amber concoction, Bergamote 22, instead.

These cologne devotees never forget to spritz themselves before leaving the house. When Mota-medi's in the shower in the morning, he decides both what clothes he's going to put on that day and what fragrance he's going to pair with them. There are rules: He won't wear the elegant iris-and-sandalwood Creed Green Irish Tweed with jeans and a T-shirt and won't match Bergamote 22 with a tuxedo. "My scent defines how I want people to take me in," he says.

Motamedi stores his collection in the refrigerator so the scents will last longer—except for the Platinum Égoïste, which he goes through too quickly to warrant preservation. "My freshman-year roommates were nervous they'd drunkenly open the fridge and break $1,000 worth of fragrances," he says. "Ninety-five percent of my friends don't get it." Chris Fisher's buddies are the same way. "You can't even have conversations with them about fragrance," he laments.

If you'd rather not bring up the subject with your guy friends either, but are curious about what scents the neophyte collector should start with, Fisher suggests three. For everyday use, get a light, citrusy fragrance like Acqua di Parma Colonia. For night, pick a spicier, more noticeable one, such as Terre d'Hermès. And to round out the collection, find a scent that you connect with emotionally. For Fisher, it's Pinaud Clubman.