first off , weclome fellow MOFO (that's short for Missouri folk)
Now, in an attempt to answer your question. I would discount his theory. If he is offering a heavy weight barrel, that wouyld be a good thing if you had a way of verifying that claim. I wouldn't worry too much about the barrels containing varnish. Varnish will burn off relatively easy. Enamel or epoxy lined barrells, on the other hand, can be a bich to burn out.
Personally, if I were you, I would also be considering the driving distance to get a barrell. If there was only a coating of varnish in an otherwise unlined barrel and it was relatively close by, and its a relatively heavy guage barrell, I recommend you go for it .
Dr. Mark (STL)
Ph.D. (honorary) Bovine $hitology
A thin line separates paranoia from an acute understanding of reality.