So in this here essay:
Laurie Penny describes sexists as “mouthbreathing manchild misogynists”. It seems to be fairly common to describe racists and/or sexists as “mouthbreathers”.
I don’t see why, apart from unconscious ableism, anyone would use ableist slurs to denounce racists and sexists. I grew up with severe allergies and severe asthma. Do the biology. I grew up only being able to breathe through my mouth, ‘cause I don’t have gills, and I didn’t have any ability to breathe through anything else. So personally, I don’t like that word.