(I wish there were some decent examples available online--if there were, I would put a pushy link here.)

I have both read some of Lovecraft's letters and been (with rushthatspeaks) to Swan Point Cemetery, although that should not stop you from evangelizing. I think part of the point of confusing Lovecraft with one of his own characters is the buildup to the final letter, which you will note changes tone entirely, as if he were trawling for the eldritch horror with his prose; I am charmed by it nonetheless.