Hey I have a Supernatural question for you! I'm sorry if you've already answered this, I'm a recent follower. At the end of season 8, when Sam is trying to cure Crowley of being a demon, obviously he didn't end up finishing the job but why didn't the boys ever go back and try to cure him again? I understand why Sam couldn't but why didn't Dean or Kevin purify themselves and try to cure him? Crowley was addicted to human blood for a while so why not just carry out the whole ritual? Thoughts?
Actually I haven't answered this before and it's a great question, thank you for asking! I think there are a couple of reasons they never cured him. The first is that there are moral issues with using the cure
Father Simon:Â A demon is a human soul, twisted and corrupted by its time in Hell. Father Thompson believed that you could wash that taint away and restore their humanity.Dean:Â So, what, they just stay in whatever schmuck they're possessing and -- and get a ticket upstairs?-Clip Show 8.22
The cure can turn a demon into a human soul, which gives that soul back to heaven, but they remain in the body they were possessing. What happens to the original human? Do they die? Do they stay trapped in their own meat suit while the demon lives out the rest of their life? And the fact that the demon-turned-human gets to live as a human for a while means they can always damn their soul again. Doing the cure on Crowley wouldn't make him good, it would just make him human. He might decide to turn his life around and be a good human, or he could decide he preferred being the King of Hell and sell his soul again. The only way to  guarantee that a cured Crowley would go to heaven would be to kill him as soon as he turned human, before he had a chance to taint his newly cleansed soul
The second reason is that they kept Crowley alive because they thought he might be useful. In I Think I'm Gonna Like it Here 9.01 Dean was planning to use Crowley to cure Sam until Gadreel showed up. They later utilized Crowley's demon powers to help Sam kick Gadreel out and to find the First Blade. These are things he couldn't have done if he was human.
The Winchesters have a begrudging acceptance of Crowley as an occasional ally but they don't consider him a friend. The only reason they'd have to cure Crowley would be to give him a second chance at getting into heaven and I don't think the Winchesters feel he's deserving of that. As a demon he's occasionally useful, as a human he's not. Plus they'd have to worry about him selling his soul again. He knows how to work the system, human!Crowley could negotiate a deal to make himself incredibly powerful. As a demon they know how to kill him if he gets out of hand but if human!Crowley worked a deal that makes him immune to their weapons they'd be powerless to stop him. As the old saying goes "Better the devil you know than the devil you don't"
