Well, it depends, Teresa. Were the rocks quality? As in, did they make good pets?
I still believe success is some indication of the quality of the work. People bash Harry Potter all the time, but it was hugely successful, which means that a LOT of people thought it had quality. I mean, there are outside factors that can prevent quality work from getting published, but if it really is quality, it will sell. And if it doesn't, it means that it wasn't marketed right. But if it is, quality will sell.