Never boiled my cotton. With regular organic cotton though, I've noticed it needs to be "primed" a little bit. Like after replacing the cotton I'd soak it up with
e-liquid and then kind of just burn it all off without actually
vaping it. I noticed a papery taste from the cotton if I'd
vape it in that first soak.
With Japanese cotton, I've noticed that's not really necessary. There is a
slight flavor to the Japanese cotton but it's nowhere near the regular organic cotton -- which would sometimes taste weird for longer than the first 2 drippings.
So yeah, never boiled my cotton. I suggest using Japanese cotton or Rayon. Organic cotton works fine too, but the "break in period" papery taste thing is a bit annoying.