"Because many pheromones involve chemical secretions that are "smelled," or have a smell, this has led to the erroneous conclusion that pheromones are odors, which they are not. Pheromones are chemicals which may or may not be smelled at all. It is also the case that pheromones are not normally picked up and processed by the olfactory system, but rather by a separate structure called the vomeronasal organ (VNO) which connects to the accessory olfactory bulb, an independent structure from the main olfactory system. The VNO is located above the roof of the mouth and evolved to detect large molecules and molecules that are dissolved in liquid, which is why licking various body parts-as dogs do when they great each other-- is a key way for pheromonal information to be received. We can only "smell" with our nose small airborne molecules." - Lit

"All animals that have been documented to use pheromonal communication use their VNO for detecting them. One major problem for creating our billion dollar pheromonal potion is that we do not have a functioning VNO. Human embryos may have a VNO, but after birth this tissue disappears. There continues to be controversy surrounding this issue, but overwhelming evidence points to there being no functioning neural tissue in humans that corresponds to the VNO of other animals. Moreover, although it may be possible for the main olfactory bulb to process pheromones, the accessory olfactory bulb to which VNO nerves normally project, has not been found in humans." - Lit