I saw your question on the "hypnotic immobility" thing - I also used that to calm and dispatch my roo. Meat classes taught me that a stressed animal equals poorer quality meat, and I've found that true with deer hunting (a quick dispatch vs a injury and needing to have a second shot dispatch means some quality differences in the flavor and texture of meat). ANYWAY, grab the chicken by the feet, and if moving, I've found it helps to somewhat support their head. They go limp in a second or so. Calmly and quietly hang them feet up, and they will just hang there without moving, and often will shut their eyes.
He is quite alive in this picture.
I prefer to use a scalpel to cut the jugular - I know its super, super sharp, and will not mean me hacking away at the throat with a dull knife. Also, have you ever cut yourself with a very sharp knife, only to find out after you've bled all over the vegetables? No pain with a clean cut.
When I dispatched this guy, I held his head for about 15 seconds, and he never flinched. After a minute or so, he flopped a bit, but I believe that was more excess nerve energy twitching muscles than him actually being alive.
I didn't notice much smell when wet plucking, but then, I keep their area pretty clean, and there isn't exactly a ton of chicken poo on them to scald. I also add dishsoap to the scald water, and honestly, he kinda smelled like Dawn.