Yeah, I'm not getting the issue with this one either. They're renting out their house for $40 a night, which is nothing, if the people are willing to watch the dog. If I wanted to stay in that area for a month, that seems like an affordable way to do it as long as the dog sitting expectations aren't excessive.
As someone else said, looking after people’s pets when they are on holiday is a job. They should pay you to do that, not you pay them.
You can pay people to pop round a few times a day to feed and walk the dog and then clean up after them. I’d imagine that adding an overnight stay to look after them would be more expensive too.
So they basically want you to pay them for the privilege of looking after their dog.
They could get someone to drop by and feed the dog a time or two a day for fairly cheap. Their house is apparently one they list on air b&b, and if wager for way more than $40 a night. So the pay is the giant reduction in cost. Financially, they would probably come out ahead if they put the dog in a kennel and rented out the house. Instead they're offering something else.
Wouldn't be desirable for everyone, but I bet there will be some who jump at it.
I wonder if some people are mad about this because they read it as "please come take care of my stuff, and pay me for it". I read it as "Do you want to rent in the area? I am willing to give you a steep discount if you also take care of my dog."