I find this thread interesting as to what people think is a good bass demo for their subwoofers. I used to be thrilled by the wow factor of deep bass in movies. Rattling windows and shaking floors. But now my criteria is whether or not the bass in the music sounds clean and appropriate. Nothing is worse for me than booming bass when listening to music; as I listen to more music than watch movies.
That's my take on the criteria for a good sub.