Listerine's flipbook campaign in Hong Kong releases the scent of bad breath. The campaign had an attractive girl showing them the book, and as the pages turned, they would emit the scent of onions. At the end of the book, the person was offered a coupon for a free bottle of Listerine. The coupon's redemption rate rose to 66 percent.
For another halitosis campaign, check out the Tic-Tac flash mob.