I don't know what that smell is. amd I've been trying to figure it out. It isn't a bad smell and it isn't strong--it just grows and grows and sticks in my nose until I wake up the next morning. I thought maybe it was the smell of the entrails, but now I'm not so sure. This morning when I hosed down the area (again) that I had bled them out, I could smell it and it took forever for me to stop smelling it. It isn't the smell of blood, either. It's not the smell of dirty wet feathers because I have only skinned my birds.
I think it was this thread that I was on where I saw the solution to this. Someone on here has the same problem as you and they wore a dust mask with a few drops of essential oils on it which cut the scent, so maybe some lemongrass or something like that that you ENJOY smelling would be better than that death smell... I've never butchered anything, but I've helped my dad skin deer and I think I know what smell you're talking about, I can still smell it on my hands the next day even with washing and all.