Those poor pups, it's really sad they were handed back to that lady to sell, I can't imagine the place they came from was cleaner. She clearly doesn't care about their health taking such young & unvaccinated pups into environment where has no idea what viruses previous dogs/people may have carried in.
I feel so sorry for the house owner having to clean that up and even if had allowed multiple dogs you'd not expect someone to bring a couple of litters and pretend they live there to sell them but it does seem to happen frequently. I can imagine angry buyers turning up disturbing other renters wanting to complain about their sick puppies.
Not great for us dog owners looking for a holiday let either in future as you wouldn't blame them for switching to 'no dogs' although I doubt these puppy farm sellers pay much attention to the rules.