I'm currently hosting long-term guests for 2.5 months in our "no pets allergy-friendly" Bungalow. They booked FIVE months ago, but informed me 2 days before arrival about their "Service Dog".
I had never encountered the "service animal" situation before, so I had a very quick learning curve to find out -- anyone can bring their "Service Animal" without giving ANY notice whatsoever, they can just turn up. However Airbnb asks they let us know as a courtesy.
Airbnb told me I can't refuse on the basis of allergies, but we're still going back and forth on this subject. Our Bungalow is separate from our main house so it's perhaps not considered a "shared space" -- however we advertise it as "allergen friendly" and clean/launder using non-toxic unscnented products.
Our next gues... arriving immediately after the current folks leave... is allergic to dogs, which I know because she's a return guest and mentioned it last time. So this puts in an interesting dilemma, and I'm not sure how it will work out just yet.
At the very least I'd like the opportunity to go in the Bungalow part-way through the stay to see if it... smells of dog! Which I know will be a huge problem for my recurring next guest. Sigh. It's not like I'm offering a "public space" which per ADA Rules is what it should be. This is frustrating.