Androstenone is found in high concentrations in a male pig's saliva. When a female pig that is in heat smells this, she assumes the mating stance. The vameronasal organ is the auxiliary olfactory sense organ that is responsible for the detection of pheromones as more than just an odor. Which basically acts as an aphrodisiac! Too bad humans lack these sensory cells needed to detect pheromones beyond smell.

Also, the reason why people both smell a boar's smell and have two seperate, distinct discriptions is the fact that there are genetic differences in our OR7D4 receptor, which detects the chemical. People that possess two proper genes for OR7D4 tend to describe the odor of the steriod as a urine smell, where those with only one proper genes tend to describe it as weak or not able to detect it.
Sorry, I think I got off track a little...thought some of ya'll might find it interesting?!?!