I find it strange that folk go on about vapers tongue when they do not go on about drinkers tongue or eaters tongue and we did not care about smokers tongue. The distinctive taste of beer or wine goes after a couple of glasses unless we change drink. It is just how tongues work in conjunction with brains. The tongue/brain wants to know that a new taste is safe to eat/drink/breath and once it has been established that there are no off flavours the tongue/brain is less responsive unless the flavour changes. We do not taste the water we normally drink or the air we normally breath but might notice when we go somewhere new. Vapers tongue is just normal tongue and it is only a problem if you decide to make it one.