could be like a sensory thing too, like, idk, it’s a little less wet to kiss someone after they’ve had a cock in their mouth vs a pussy. you get a lil messier and the sensation might just make you feel icky, or you might not like the taste

unfortunately, OP, we can’t answer for you, but i would caution you from assuming it’s some kind of belief-based disgust or like, a superiority thing, or whatever