I tend to see inanimate objects as "happy" if they are fulfilling their purpose, so a sofa would like to be sat on. I mean, think about the toilet! It is doing it's job though. It's objects that don't or are being neglected, that I feel more sorry for. It's like Toy Story - the toys just want to be played with by a child and bring that child joy and all is well as long as they are doing that.