I went over a majority of images under the penis pubic_hair tag search to provide a breakdown of the types of images that can found. Hopefully this might help in deciding things such as definitions and necessity of tags that are associated with the pubic_hair tag.
Category: Number (Percentage) [Projected Number]
Male w/ Female Both Visible Pubic Hair: 470 (30.60%) 
M w/ F Only M w/ Pubic Hair: 86 (5.60%) 
M w/ F Only M's Area Visible w/ P Hair: 289 (18.82%) 
Male Only Images: 15 (0.98%) 
F w/ M Only F w/ Pubic Hair: 161 (10.48%) 
F w/ M Only F's Area Visible w/ P Hair: 435 (28.32%) 
Female Only Images (Mistagged): 1 (0.07%) 
Futa w/ M or F Only Futa w/ Pubic Hair: 4 (0.26%) 
Futa w/ M or F Only Futa's Area Visible w/ P Hair: 16 (1.04%) 
Futa w/ M Both w/ Pubic Hair: 3 (0.20%) 
Futa w/ M Only M's Area Visible w/ P Hair: 2 (0.13%) 
Futa w/ F Both w/ Pubic Hair: 5 (0.33%) 
Futa w/ F Only F's Area Visible w/ P Hair: 12 (0.78%) 
Futa Only Images: 20 (1.30%) 
Newhalf Only: 1 (0.07%) 
Unknown*: 14 (0.91%) 
None (mistagged): 2 (0.13%) 
*: Images tagged pubic hair but either highly censored and thus hard to determine or images that depict a situation in which pubic hair is present but which character or characters the pubic hair belongs is not determinable.
Gender's (F/M/Futa's) Area Visible category indicates that in the image that only that gender's area that would have pubic hair is visible and thus can be determined.
I should have kept track of it, but Images with F w/ M where only Females had pubic hair was influenced by images of straight shota but it was less than I expected (perhaps only accounting at most less than half of the images). Likewise loli had an impact with the male equivalent category, but again should only account for around less than half those images. Male Only Images tended to be yaoi images.
There might be a very slight error with the Male w/ Female Male's Area Visible category, since I may have overlooked some traps and placed them in this category. Many of those situations for this category had the character fully clothed, so going by visuals alone they'd simply look female unless you checked the tags.