yeah, mom told me

but remember how long people thought you could die from being covered in gold paint?
additionally, it may have something to do with flawed korean housing and heating (heated floors) which could have easily caused any number of carbon monoxide deaths, etc. causing enough "evidence" to perpetuate a certain amount of valid legend.
i don't think there is a realm of myth or supersition like gifts of knives as much as chronic housing problems at a certain point in time
but then my theories on japanese ghost stories and demons are a bit non standard as well