This is Wikipedia's definition of conspiracy theory:
A conspiracy theory is an explanation of an event or situation that invokes an unwarranted conspiracy generally one involving an illegal or harmful act carried out by government or other powerful actors. Conspiracy theories often produce hypotheses that contradict the prevailing understanding of history or simple facts. The term is a derogatory one.
What kind of fallacy does this qualify as? Or is it not a fallacy at all but some other kind of mind game?
There could actually be two or three fallacies at work here. The key word in the first sentence is unwarranted, while the key word in the second sentence is often. Finally, we're told that "conspiracy theory" is a dirty word (derogatory).
EDITED to put this in better perspective. Here's Merriam-Webster's definition of conspiracy:
a theory that explains an event or set of circumstances as the result of a secret plot by usually powerful conspirators
It's simple and to the point. There's no obfuscation or name calling involved. Wikipedia clearly jumps through several hoops in trashing that definition. Yet no one here can identify the fallacies involved?