I allow pets in my place and have had a few problems. I didn't, however, have any problem getting an extra $25 out of the regular security deposit when two guests with a dog left leaving a large pee puddle on my living room rug behind. It took at least an extra hour of cleaning for me. I wrote and asked them to send $25 more and they ignored my request. I put in a request to AirBnB for the money from the security deposit and it arrived in my account very quickly without any further questions.
I DO think there should be two (simple?) changes in the AirBnB booking system. One, people with pets need to let me know ahead of time. If you have children with you, it shows up in the booking info. If people have pets and don't mention it, they can show up without hosts having any idea they're coming with dogs or cats or ferrets or parrots. I like to cover my couch in advance with a large sheet that's easier to deal with than the tightly zipped cushion covers. There should be a box to check if people are checking in with pets and THAT should trigger an additional security deposit or an additional fee automatically, depending on what the host wants. For example. people without pets, $75 per night plus cleaning fees. People with pets, $75 per night PLUS an additional $20 cleaning fee and an extra $200 deposit to charge against if there is damage.
I have a dog and I'm very aware of the need for and relief at places that accept dogs. I also know that there is almost never a time I have someone with an animal stay in my rental that I don't need to spend extra time cleaning up hair, dog food, poop in the yard, etc. I try to be EXTRA careful about my dog, but not everyone is.