User blog comment:Winchester7314/Possible plot-hole, or maybe a deep hidden reason?/@comment-24.140.27.113-20131013160729

They cannot be broken, no they can't. But Demons aren't souls that are "broken." They are souls which lost their humanity. They are so evil that the good in them has been tortured out of them, so Death is still correct. They cannot be broken but they can be changed. I'm sure that someone could take a soul and pamper it in Heaven to create a completely different being but that being would still be a human soul.

And I'm sure what Pagan God meant when he said to Crowley was that he doesn't have a soul to trade in the sense that Crowley does NOT have a human body. Which means that his soul is as good as a human wanting to trade their body. It doesn't have any sustenance to it.