I am having almost the EXACT same issue. I state clearly in my listing that I have a dog, and am definitely going to add a picture of said dog after reading several posts on here. However main issue I am having (on top of the guest exploiting my provided breakfast by eating almost an entire very large loaf of bread - or using it to make lunch maybe?) is his allergies.
Not a peep beforehand about any allergies. Morning after the first night he tells me he slept terribly because when he went to bed his asthma kicked in in the night and it got worse throughout the night so it must be something in the room as before this he hadn't used his inhaler in months. He then managed to tell me he is super allergic to "house dust" i.e. dust mites, and slightly allergic to pet dander, but he didn't think it was the dog. I was shocked - the room was squeeky clean as in you could do the glove test and you wouldn't find dust, the mattress/bedding/sheets were either new or freshly washed (at 80 C). However, I had a goose down pillow and duvet on the bed, and I wash the curtains only 3 times a year, so I told him as much and said I would remove the curtains and goose down, replace them with synthetic bedding, replace all the sheets and duvet covers and curtains with freshly washed ones and wipe-down everything and vacuum again.
Fast forward to the next morning. He slept well no problem - clearly the problem was the goose down. And disclaimer here, the goose down is not old, and nobody in the last two years of friends and now more recently airbnb guest has had any issues.
Only now he's actually sure he's allergic to the dog, as he feels that now everytime he goes near her it gets worse. Why the changing story now that the room is ok? On top of that he has suggested that he thinks I let the dog go in that room - she NEVER goes in there and she is NOT allowed on any furniture, especially not beds. But if you live with a dog, there will be dog hairs around, just like we humans lose hair. I told him as much and I told him kindly that I would make sure to vacuum every afternoon to try help with that
WHY would you book a room in a place with a dog if you are allergic? And its not like he didn't realise there was a dog, he knew. I'm really frustrated as the dog is part of the package and it is clearly stated. He knowingly made a bad decision because he was too cheap to go to a pet-free place or a sterile hotel. I lose out on everything - triple the work, and probably a bad review in the end despite all my effort.
I will have to include a house rule of no allergies to dogs or something - anyone have any other advice?