I used to date this guy who had to wash all of his clothes with Tide and Downey, before he could wear anything they had to go through this scent producing procedure. He would walk around lifting the neck of his T-shirt up to smell it throughout the day. The scent of this combination was so distinct for him, it carried him away to a time of safety and acceptance. His mom did all his laundry growing up and even laid his clothes out for him each day and for him it symbolized the absolute love she had for him. All he needed was a whiff of that fresh scent to bring him back to those feelings.
When my hands smell like onion and garlic after a day of cooking, I smell them all day long, not wanting to remove the feeling of being with my mom or grandmother cooking and singing and laughing as a child.
When creating a brand you are trying to make people feel a certain way when they think about or see your brand. For my old boyfriend the Tide/Downey combo did just that, he associates those brands with comfort and safety. More than any other sense, our sense of smell is the sense tied most closely to memory and emotion. Smellovision may be a little too contrived but every candle company, real estate agent, hotel chain, and perfume company knows that finding a way to tap into the instinctive positive emotion and memories through smell is a great way to get your customers to associate you with the feeling you want them to have.
Maybe your product already has a smell, what is the emotion evoked from that smell? Does the rest of your marketing support that feeling?