Astolfo said:
Hm, that's a valid oversight. Even so I definitely don't think it needs to get into the territory of male_furry_on_female_humanoid or such overly precise tags.
If the problem then becomes filtering out yaoi or yuri can't you just -yuri or -yaoi in your search, or blacklist them?
"anthro_on_humanoid male_anthro -yaoi" and you only get anthros on human(ish) females, "anthro_on_humanoid female_anthro -yuri" and you only get female anthros on guys?
That assumes that these tags are going to always be used, which in reality is not true. We used to have the same issue with dark_skin, when we didn't have dark-skinned female and it was assumed that dark_skin -dark_skinned_male would only find women. This in practice was wrong because people often don't tag male-specific tags in female-focused pictures, especially the explicit ones (1girl -dark-skinned_female -dark-skinned_male dark_skin rating:e nowadays allows us to see how bad it really was).
Let's look at the possible cases:
[*] interspecies is a bad filter because it's often missed, so it becomes a game of cat and mouse to fix mistags while you're browsing for content, which is not very fun if you're looking at porn tags. "Fix the mistags when you see them" is not a very good argument when talking about fetishes, especially ones as strong as furry. Remember, furry -rating:s is one of the default entries in the blacklist.
Of the 7 possible combinations, 5 are already technically searchable, albeit with mistags because you have to rely on a three-tag search to make it work. In these, adding male/female furry would be padding.
The two combinations that are impossible to search for right now are male furries on female non-furries and female furries on male non-furries. Basically hetero interspecies. Obvious hetero interspecies is not a substitute due to the amount of things that technically fall under interspecies.
In fact, interspecies causes issues for the other 5 combinations as well because things like pokemon (creature) on pokemon are also interspecies while also being furry on furry (think lucario on gardevoir). The wiki says "Sex between a human and a non-human, but humanoid, species" but good luck enforcing that when people routinely mistag even bestiality with interspecies and viceversa. I don't think interspecies in general is a great idea of a tag because of how generic and prone to mistakes it is.
So, it might make sense to use male_furry/female_furry, but then you end up with, for example, male_furry yaoi, which is same amount of tags as furry_on_furry yaoi.
Of the two currently impossible combinations, the only one that I can see working is male_furry hetero -female_furry, and with a big question mark, while I can't see female_furry hetero -male_furry ever working given what we've seen in the past. As mentioned before, and in the dark_skin example, people frequently miss male tags. You only have to look at 1girl sex -1boy -multiple_boys to see how often people forget to tag male features. I'm not very enthusiastic about having to spend hours looking at content I don't like to fix mistags just to find what I want, and I spend way too much time on danbooru already. I can't imagine the average lurker would ever want to do that.
The only positive side I can see for male_furry/female_furry is as a replacement for 1boy solo furry and 1girl solo furry. For the purpose of this thread they wouldn't help at all, imo.