Overall we enjoyed our stay in Madrid and Carmelo's apartment. It's a great starting point to explore the city. Yes, it's noisy but that's the trade off for being in the epi center of Madrid.
Communication with Carmelo was quick and easy before as well as during our stay. Pictures are accurate and place is clean.
An issue which I trust is temporary and Carmelo is going to fix is a bad smell coming from the shower drain. Hence we have to deduct a bit on the rating as this really impacted our experience.