There are many categories in porn that nobody touches! All the extremes for example, I think the average human being is not interested in watching a woman sucking a horse's cock, or getting it from a dog... or I could mention the vomit or scat fetishes as well, and there are some other types too that I do not even dare mention! The average Joe watches deepthroat and anal action with possible threesome and occasional lesbian porn, or teen porn, that's it!