There are many myths about the PPC. Being myths, they are not actually true.
Many of these are also addressed in the FAQ: For Other People.
Myth: PPC agents are Mary Sues.Edit
Truth: PPC agents may be self-inserts, but they are required not to be Mary Sues. Getting permission to write spin-offs involves having your agents reviewed by experienced PPCers who can smell a Sue or Stu a mile off. If your agent has Sue-like traits, you simply don't get permission. Drifting into Sue territory also has in-character repercussions: An agent who becomes even slightly Sued is detected and treated ASAP. Any PPC agent who becomes completely Sued usually ends up... disappearing.
Remember that a self-insert is not necessarily a Mary Sue. In fact, Intel has on at least one occasion investigated a fic in which a self-insert was not a Mary Sue and her home fic was deemed goodfic. Self-insert agents are required to be realistic characters, with all the faults and quirks of their authors, rather than the idealized self-insert which often ends up becoming a Sue.
Myth: PPC agents are all self-inserts.Edit
Truth: Some are; most are not. When the PPC was first invented, most agents were self-inserts; but Jay and Acacia set the precedent for recruiting minor characters. As time went on and we learned more and defined the PPC more completely, agents increasingly were rescued and recruited from badfic. Today's agents may be from World One without being self-inserts; others may have been recruited from badfic (hypothetical or real) and given personalities of their own. Some are even reformed Mary Sues. Yet others dropped into HQ through plotholes from any of the myriads of continua that the PPC protects. The PPC includes agents of many species and origins.
Myth: The PPC exists only to kill Mary Sues.Edit
Truth: Assassinations were the first recorded PPC missions; but the PPC actually exists to repair the damage caused by badfic, and killing a Sue is only required some of the time. The Original Series also introduced exorcism (removing slash wraiths from bad slash stories) and untangling bad crossovers. Since then, other kinds of missions have been written. Despatch retrieves canon characters kidnapped from their home universes. The Department of Technical Errors repairs bad-grammar damage. DOGA is known as the Pyro Department because they remove non-canon locations and geographical aberrations. The Troll Division deals with trollfic by removing the troll from the continuum, and the MPreg Division of Bad Slash uses the debugger to remove biologically impossible pregnancies (these are taken to Medical and then raised in the Nursery). Of course, there are also infrastructure departments whose agents don't go on missions—everything from the Postal Department or the Cafeteria to DMSE&R, the PPC's science organization, or the Department of Sufficiently Advanced Technology, the PPC's engineers.
When dealing with Suefic, agents usually do kill the Mary Sue or Gary Stu involved. This is necessary because repairing the continuum requires removing the uncanon elements, and a Mary Sue is a phenomenon too dangerous to take anywhere else. Occasionally, though, a Sue or Stu will have a rudimentary personality and the potential for sentience, and can be rescued and rehabilitated. The PPC's Sue Support Group helps these ex-Sues stay on the (non-glittery) wagon.
Myth: PPC writers make fun of badfic because they are mean-spirited and want to make people feel bad.Edit
Truth: Let's look at it this way. You're a fan of a certain verse. You love everything about it—the characters, the setting, the feel. But the author can only write so much, so you turn to writing and reading fan fiction to get more of the same, or to explore the corners of the plot that went unexplored, or to flesh out minor characters. But in this fandom, there are people who write stories that are full of plotholes, in which Mary Sues take over and make the canons into inconsequential boy-toys, and in which bad grammar runs rampant. Since you went through your own Mary Sue stage when you were first writing fanfiction, you talk to the author and explain what they could change to make the story better.
Except... the author doesn't listen. Instead of trying to improve, they claim that it is "only fan fiction" and doesn't need to be proofread, that their Mary Sue is perfectly realistic, and that it doesn't matter that they turned your favorite character into a homophobic jerk in order to get their favorite slash pairing together, because they can write whatever they like. You just get really, really tired of seeing your favorite world twisted around like that, and meeting people who think that this is good writing.
Writing missions is, simply put, cathartic. You get to send your agents into the world and patch up what the badfic author damaged. You get to see the continuum turn back into what it ought to be.
In addition, we have a policy of not notifying an author if we write a mission based on their fic, to emphasize that we do not write missions with the intent of attacking the author. In fact, it is quite possible for an author with a fic bad enough to spork to also be responsible for goodfic.
PPC authors have an active beta reader network and are always available to give concrit on fan fiction. We don't presume to think that writing missions actually does anything about badfic; but beyond writing missions, we do want to improve the quality of fan fiction by teaching people to write well.
Truth: We call it the Department of Bad Slash... implying that there is good slash. In fact, Bad Slash exorcists are mostly written by experienced slash writers and readers—they have to be able to know what makes a slash story good or bad. Bad slash has specific problems that pop up again and again—taking characters OOC, whether the slashed couple or the significant others of one or both, those around them, or the world in general. In many cases, bad slash stories have some very unfortunate implications. It's not unknown for possession to force characters to adopt gay-stereotype personalities they never had before, to push them into seme/uke roles that they do not fit, or to warp those around them into Unrealistically Tolerant Pillocks and Token Homophobic Jerks. In some cases, authors don't research the mechanics of sex between two men and commit errors of bad biology which should be anywhere from uncomfortable to outright fatal. Bad Slash missions correct these errors.
Myth: The PPC is misogynistic/anti-feminist and hates strong female characters.Edit
Truth: The FAQ really covers this one. Go read it, seriously.
Truth: This is strictly against the rules. PPC authors are not allowed to write any story in which a real person is killed. Agents assassinate Mary Sues, but because they are so badly written, Sues don't actually possess sentience. Killing a Sue is not murder, but killing her author would be, and assassins are not murderers. PPC agents don't interact with authors more than necessary. Despatch may occasionally have to relocate someone capable of Trans-Dimensional Hopping or use a neuralyzer on someone who has kidnapped canons. Badfic authors are often sent to an OFU to learn how to write properly. Other than that, the PPC doesn't really touch authors that much.