Going back to answer one of the original post...
In my experience, burning plastic taste and smell could be present for couple of reason. One is the primer fluid that comes with the new atty to protect the atty from drying which will go away after a day or so of
vaping.
The other reason is when the opening tip of the cart touches the hot atty. I think what you could be
vaping is the melting cart.
I usually just align the opening of the cart with the atty (=) so that both atty and the cart will will not create contact (+). I hope I am explaining this right...
You will know when your cart has burnt when you see the melted tip of the cart.