Yes I do charge for pets.
I use to ask the guests to add the pets in as guests. I would charge £7 per night. This is very reasonable.
However, AirBnB has now created a very confusing and contradicting pet payment service.
Initially it comes up "Price is added to PER night price", but when you actually get paid its only a one off charge. Example: I put in £7 thinking its £7 per night. I actually got £7 for the whole trip which was 55 nights. I got robbed.
So when I went to increase the pet charge, a message pops up saying you cant go over your Per night price.
The pet charge should be per night. This way the guest pays for how many nights he stays!