Holy water + Demons = Smoke and hissing sounds. Does that mean there would be a smell like burning flesh, you know, like a barbecue whenever Sam and Dean throw Holy water on demon possessed humans or is it completely odourless, which btw just doesn't seem quite as awesome as barbecue!demon.

Yes, this is a very serious question in relation to demonic possession in Supernatural, it has been driving me crazy since 6am in the morning.