It's unfortunate that "conspiracy theory" is so loaded with negative connotations. Alas, legions of whacky conspiracy theorists have helped made that happen.
I suggest we all just accept the fact that EVERYBODY understands the term the same today: It is derogatory short hand for people who claim a criminal conspiracy that is NOT TRUE. That "not true" bit is implied by the term "conspiracy theory".
If you want to theorize about a proposed conspiracy that is actually true, or at least plausible and not yet debunked, you surely will avoid saying you have a "conspiracy theory". You would say "a theory involving a conspiracy" instead, or whatever gets the point across without using the loaded term.
In fact, I have found it useful to consistently adhere to a strict definition of a related, more specific term:
DEFINITION: A "9/11 Truther" is a person who persists in being essentially wrong about 9/11.
Each word in that definition is necessary:
"persist" implies that you are not a 9/11 Truther if you initially are wrong about 9/11, but are able to and do revise your stance once you obtain more and better information. Everybody can be wrong about anything for a while.
"essentially" recognizes that some/most/all "9/11 Truthers" are right about some details and aspects of the larger topic (e.g. almost all acknowledge 9/11 occurres on 9/11/2001, involved major destructive events in NYC, and that the sun shone from a blue sky. Being partially right does not suffice to not be called a "9/11 Truther", if you persist in being wrong about the essence of they events: If you deny that people dies; if you deny airiners were used; if you blame it on Jews, you are wrong about the essence of 9/11. Conversely, you could be mistaken or ignorant about some details and aspects, while understanding the essentials. Such ancillary wrongness would then not make you a "Truther".
Try this definition on Truthers and non-Truthers of all stripes: You will find it really captures what you already knew the term "really" means.
So I suggest someone coin a broader definition of the term "conspiracy theory" that captures that its adherents persist in being essentially wrong when proposing a specific or unspecific conspiracy is to blame for some societal ill, such as a major crime or a public crisis.