Staying at Carlos' and Madalena's place is exactly as you will read in the other comments: laudable.
The bungalow is in the back of their own property with a small pathway leading up to it giving you all the privacy you need. It's well-furbished, clean, calm, very close to Sintra (walking distance to the center, the station and the principal must-sees).
What added extra value to our stay were Madalena's and Carlos' tips: where to eat, where to shop, what to see and how to get round. The only thing we regretted was not booking Carlos as a guide during our stay. I guess we will have to come back. ;)