I stayed in Carmen's place while working in Barcelona for two months and I can't recommend it highly enough!
The pictures make the apartment look nice but it's actually much more impressive in real life, high ceilings, large rooms and very well decorated. I did not know much about the area before arriving but Clot is really nice, very safe, friendly, with great bars and restaurants without being too 'touristy'. It has great travel connections to the airport and the city centre too. Carmen and Olivier are both very nice people and made me feel really welcome.