The trouble with Deadwood is that the world implied by the characters doesn't match the world the show actually gives us.

I simply do not understand this. Because they speak in iambic pentameter? That seems a terribly dogmatic quibble. How does Al not fit in his world? How does Bullock?

It doesn't help that you're defense of TWW's similar sin is entirely unconvincing - sure, TWW was clearly set in a parallel world. So is, erm, Deadwood. I don't understand the difference, except you like TWW but not Deadwood. For subconscious reasons other than those you're stating. Or something. :P