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Of course that doesn't have to do anything with Sam not having a soul. I was simply elaborating on the fact that Dean does have a soul. His actions and feelings make it clear that he does have a one intact. For example the love he has for Lisa and Ben. Someone without a soul wouldn't be able to feel love or have compassion for another human being.
Sam on the other hand let his own brother get turned into a vampire and put the people Dean cares about in danger just so that he could get information that he wanted. Lets not forget that he also made no objections about Cas torturing the boy in the episode "The Third Man" to get the information they needed. Again, soulless person has no feeling. Sam said it himself in this episode, "I just don't feel anything".
I get what you are trying to say with Famine though. Remember though, Famine, aside demons, ate human souls but he didn't want Deans because his SOUL had no life in it. In season five Dean was "dead" from the inside because there was nothing in the world that could bring him happiness. Dean was in a funk because he knew that he and Sam started the Apocolypse and they wanted to stop it but had no leads, they were sitting ducks. He knew they were doomed cause his mentality was "How do you stop the DEVIL?" He was hopeless, lifeless and dead from the inside.
Man, I hope I am not coming off as rude. If so, I am sorry. I just really like having conversations about this show and I have no one to talk to about it cause no one I know watches it, or is willing to give it a chance. Peace.