Ok... I will respond to this step by step.
1. "There was no indication that the host would be sharing the space with us..."?
The description CLEARLY states that I'm renting one room in an apartment (even if the apartment comprises two).
I just checked again. It is the first thing you see on my profile: "Private room in an apartment: 2 guests, 2 rooms, 1 bed, 1 shared bathroom".
I am very sorry for your disappointment but it is not my fault if you do not check this before renting.
The description does not indicate that here will be two beds available. Perhaps that's what you wanted and that's what you thought it did but again you should just have checked.
2. "The price for our individual room was comparable for the price for an entire apartment in other listings in a similar location" Really??? You can find an apartment like this in the center in the middle of the summer for 40 euros a night? Waw! Please show me...
3 "Fridge had terrible smell of rotten food when opened". Was there any rotten food in the fridge? No. That's just the smell of cheese in Europe when it is not pasteurised.
4. "Overall we were extremely unsatisfied". Ana and her girlfriend never expressed anything leading me to think they were unsatisfied. Ana's girlfriend arrived a night before her and I made her a soup, home made lemonade and even a cocktail. She kept thanking me and she even talked about going out with my friends and I (even though she ended up resting home).
The next day I went to a place in the center to get them special non-touristy-made-by-locals maps of Brussels and other cities in Belgium, which I asked them to leave after them even though they didn't. Later when they left Ana's girlfriend hugged me and thanked me again. Maybe I am easily confused but I interpreted those signs as satisfaction with the stay?
5."The listing never indicates that the host would share the space with us" See to 1.
If it is one room in an apartment one can deduce that the other room will be occupied. Again, not my fault if you didn't check that.
6. About my apartment being dirty:
Ana is making it sound like the place was insalubrious.
I will concede that I had forgotten to remove the part about my old arrangement with the lady who was taking care of the place when I was abroad, and that it is now me who does the cleaning.
I like my apartment to be clean for myself so I don't think it was "covered with dust and hair". I had cleaned it before they arrived but it is true that I could have missed a spot here and there.
However presenting it like Ana is is much exaggerated if not dishonest. Ana seems to me to be the kind of person who wants to annihilate a business when she writes a comment. Yelp, Tripadvisor and all those sites gives the opportunity to a certain kind of people to spill their frustration in the comfort of the safe little halo their personal computer light's procure them.
Again, it would have been easy to express your discomfort to me in real life (when we were having a lovely cocktail on the terrace for example). But no that would have been less fun.