All Liberalism is Perverted. If the story is set at a college, count on the dorms to be run-down and filthy, the students sex-crazed, and the school newspaper to be corrupt and its politics to the left of Stalin.
Author Avatar. Quite a bit. Sometimes dovetails with 30-Sue Pileup, with one real-world person appearing as multiple fictional alter-egos—sometimes even within a single story or series.
Subverted with Bart Camber in Postcards of the Hanging.
Ironically the author himself may quickly be approaching this trope, having started losing his hair at 23.
Beauty Is Never Tarnished. Averted often, as nearly every book contains at least one (often) graphic scene of "girl hurl". The dolls get as dirty and gross as the guys. They are frequently getting covered in mud, blood, and other unspeakable muck on misadventures, engaging in raunchy sex/talk of sex, and farting like dogs.
Catholic Girls Are Very Different From Normal Girls. Both played straight in "Smitten With Her", when a flighty young Catholic girl breaks up with a boy who tells her about the death of a loved one, though they get back together a month later... but only after he's slept with someone else, unknowingly catching HIV and giving it to her...and averted in "Dark Hunger" with another young Catholic girl who actually has her head on pretty straight (though her sister is a bit of a tramp).
In "Eve Bade Adam Eat" a man falls in love with a woman who turns out to be a coworker he got fired from the college paper nearly 30 years ago.
In Tiresias a man tells Drew Perkins about a one-night stand in college who turned out to be a young teenage boy. Drew later realizes that he was that boy. He had been manifesting a heretofore unknown and separate female personality, "Delilah", for years. Another bridge is dropped later when a second female alter-ego emerges and sends a very...interesting love letter to Delilah's currently-incarcerated phone-sex lover Antonio Mitcheson.
Got What's Comin' to 'Im. In "Dark Hunger" the vampire is struck and killed by a car crossing the street while in her cat form. It is also implied she was pregnant by one of her conquests.
Magical Negro. Bart Camber in Postcards of the Hanging, quite literally.
Muse Abuse. The young woman "Dark Hunger" was based upon completely ceased speaking to the author. This ruining of a friendship was partly caused by using information from personal conversations in the story, as well as sending her a copy of the book through her sister, whose address he tracked down using an Internet people search, which admittedly came off a bit stalky. Also, he is very harsh on his college ex, frequently portraying her in a negative light.
Shared World. Most of the stories link directly or indirectly through a character or town name; for example, the boy who grows up to be a writer in Postcards of the Hanging is the same young man Rocky chats with in Dark Hunger, and, though its never implicitly said, presumably they did hook up. Many stories are set in and around Clark, Missouri and its university. Also, the fiction world and comic-book world of The Belch Dimension, though presumably two separate realities/universes, share a few tenuous connections, such as schools, landmarks, and even minor characters. Fulkes University in Biloxi, Mississippi, for example, appeared in a short story printed in an online magazine several years before gravitating over to the comic.