I tried the PTII and the Aro Tank (two devices that work virtually the same exact way) and I simply would always get some dry, burn-ish hits. It may be some sort of mechanical residue in the tanks - they sure have a stainless steel waft if you put your nose to a cleaned tank - but I refuse to wash my tanks in any chemicals whatsoever so I have to judge it by how it performs after a distilled water soak. I tried removing some flavor wicks and flipping some gaskets, all of that, but the PTII just would not perform correctly past about 5 hits, and the Aro Tank would instantly taste burnt no matter what.
It's a little confusing because I know what dry hits taste like, without a doubt (very alike to a burning cigarette filter) but out of these two tanks, the vapor would actually taste black, burnt, or smokey (on juices that by no means are supposed to taste like that). Both devices also leaked a little from the heads a bit too much, no matter what, for my concerns - top coil devices tend to be virtually leak proof internally, and I appreciate that design much better. The one bit of good news is that the PTII is the only device I have ever used that does not leak around the seals of the glass or plastic - even my currently favored Smokin Crow leaks up a storm through top plate seal, I just have to be careful with it.
I first bought the PTII a few months back, after a period of having given up on vaping, and I read hundreds of reviews, and thought to myself "Okay, this is probably a device where there's going to be one bad head out of every 5, I can live with that." But I went through 11 heads and all of them tasted burnt no matter how much I tried manipulating and cleaning the heads without actually rebuilding. I was doing absolutely nothing wrong, my techniques are tried and tested. But this tank was simply bad stuff.