I'm very sorry about your experience. Just a few comments:
1) The house is ALWAYS aired and fully cleaned before every guest's arrival. Smell issues (it only happens sometimes, depending on the weather) are clearly disclaimed before booking and we also explain what to do to minimize it in case it happens.
This is a National Park, and there is not any public sewer system (we're fighting for it). This is why, and only depending on the wind, sometimes you can smell it.
2) The bathroom has a ventilation WINDOW (40cm x 25cm). I bet you didn't see it. But it's there.
3) Yes, it's a sub-basement, which is not only clearly said in the ad, but also in a special disclaimer that you need to accept before booking.
4) The mattresses are not old. We bought them exactly 1 year and a half ago.
5) The upstairs guests were not my friends, just nice guests that helped after an issue that I solved in 20 minutes. Twenty.
6) Regarding food supplies, food is not included in the booking (we're charging 40€ per night for 4 people accomodation). Still, you're welcome to read the 5-page restaurant recommendations and the services map (with several supermarket locations) that you had in the confirmation and that we send to ALL guests automatically when they book.
7) I'm sorry about the bed. First report was yours. You told me you heard the bed crack, so it was probably then when it broke. I would have been happy to fix that, but you only told me about it once you had already decided to leave.
8) No fused lights. I checked personally. Apparently, you had an issue with the switching. Again, we could have helped you if you had asked.
Obviously I'm sorry about your experience, but I'd ask you not to say things that are not true.
I happily agreed on Airbnb's decision to refund you 20€, since even they said it was not okay to refund you for all of second night considering the facts.
Even if we're not a hotel, we take our guests comments very seriously, and we keep working on improving their experience.