I live in Barcelona and made a reservation because I needed a place to stay for a couple of days while my flat was being renovated. However, a couple of hours after the reservation was made, I found a friend's place to stay so I didn't need the airbnb flat anymore. I contacted the owner and even knowing I made the reservation two hours back, he didn't agree to reimburse me all the money but agreed to charge only one night. I already found really abusive but ok, didn't want any problems. However, now, one week later, after I cancelled he still didn't give me my money back, even after asking for the reimbursement in Airbnb. He keeps saying he didn't receive the money request, which is clearly a lie.
Had a lot of good experiences and have been using Airbnb for a long time, but this host is absolutely NOT recommended. You will find better and cheaper places in Barcelona. RUN from it.