Flyguy, I sympathize because my mouth is about ready to be written off after 2 bowls.
I occasionally get tongue bite, and I have seen glimpses of this "acid burn" but I hope it is not a permanent affliction.
Properly drying my blends before packing my pipe solved most of my smoking problem. I always used to do it a little bit, but most blends take longer than you'd think...
It is very rare for me to smoke straight from the tin but there are instances where I feel the tobacco is dry enough.
For the most part, though, that is one of the worst things you can do. As you mention, a hell of a lot of reviewers on TR and Youtube make this critical mistake and it colours their negative perception of a blend.