If you come to Madrid, you must stay at José's place! One of my best airbnb experiences ever :)
His apartment is in a safe neighborhood a short walk from Palos de la Frontera station on the #3 line, which zips you down to Sol and Gran Via in a few stops. If you like walking, the Atocha train station (where you can connect to others cities such as Sevilla) is just a few streets away and just beyond is the Museum boulevard, including the Prado, Reina Sofia, and Thyssen.
Communication was very easy and smooth; we connected over Whatsapp just before my visit. José was home to meet me when I arrived and provided a very comprehensive explanation of the home and its features. You will be so impressed with the cleanliness of the flat. The bathroom was a highlight for me, haha, very modern! There is A/C in the summer and breakfast is included as well. The bedroom is very comfortable with a large table, floor lamp, and fan. There is even a handy system in your room to dry articles of laundry!
We had many nice conversations, as José has lived in Madrid a long time and has many lively ideas on where to go and what to see. I highly recommend staying at Josés' place.