A Lit.Thario (alternatively, Dong Juan) is a male writer who mistakenly believes that being published will directly result in sexual experiences. Back in the 1930s, when female readers were more naive and easier to manipulate, this might have been true. "Look at me, I've just published a novel! Suck me off immediately!"
A surprising number of modern writers are Lit.Tharios. They fail to understand that the girls they are vainly seeking to get into bed are probably writers themselves and thus feel no compelling need to submit to the ego of the Lit.Thario, whom they often regard as little better than a weirdminger.
There is a school of thought that claims the Lit.Thario is an honest and relatively harmless form of tactical twat, in the sense that what he wants (sex) is natural and understandable and less grasping than what most tactical twats want (power, status, ego reassurance).