>>42490455
Actually, if you take the racist obfuscation "types" literally, ponies would not have any trouble with that at all, for the reasons the show spends so much time Aesopping about in the first place.
I realized I dropped a fic like >>42490111 mentions that does it pretty clearly. The side plot in the framing device of "Five Star Service" clearly separates the Human side of the portal into bigots, those who don't care, and horsefuckers. Most of it is about who will let consenting adults do what they want to each other, but it's not a particularly small part of a large fic and it bleeds into many of the related topics you'd expect.