The Language Nazi doesn't much cotton to the loose lingo that leftists love.
Hillary spoke of a "vast right wing conspiracy" directed against her husband. Maybe that's where the linguistic mischief started. How can a conspiracy be vast and composed of half the population?
A conspiracy is a clandestine agreement among a small group of people to achieve a nefarious end, typically by means of treason or treachery. The members of a conspiracy are called conspirators. They meet in secret and in small numbers. Hillary's abuse of English is plain: conservatives do not form a secret organization; they are not few in number; and their opposition to Bill Clinton and his policies was not nefarious, treasonous, or treacherous.
A conspiracy theory alleges that a conspiracy is under way or has occurred to bring about some event. An example is the theory that 9/11 was an 'inside job.' Some conspiracy theories are true, and some false; some are well-supported by evidence, others are not. None of the 9/11 conspiracy theories are well- supported in my opinion. But that in not the present point. The present point is that it is a mistake to assume that every conspiracy theory is false or baseless.
It is also a mistake to refer to any theory or any bit of groundless speculation as a conspiracy theory. Not every theory is a conspiracy theory. A conspiracy theory alleges a conspiracy where 'conspiracy' is defined as above.
Finally, it is a mistake to oppose theories to facts, as if no theory can be true.