Personally, I think calling the Loose Change and 9/11 lunatics “conspiracy theorists” is an insult to conspiracy theorists.
A JFK conspiracy theorist has a theory based on logic and reason, and uses details and evidence to try and make it seem possible/plausible.
For example: the mob killed JFK. Because JFK was targeting the mob, there wasn’t another politician like JFK (except maybe RFK) so taking out JFK would be a radical change in policy the mob would like. The mob is capable of hiring shady people who’d kill. There were four guys on the train tracks behind the grassy knoll questioned (even photographed), but never ID’d because notes from the questioning were destroyed. They could have been mob hit men who shot JFK from the picket fence.
THAT is a conspiracy theory. There may not be conclusive evidence, but there is circumstantial evidence, logic and reason, plausible explanations.
The September 11th “conspiracy theorists” don’t have that. They simply say “we’re being lied to by the government, there’s no concrete evidence that the events happened as the government says they did.”
Which would be like saying “How do we know JFK was killed (or not?!) in Dealy Plaza? The headshot on the Zapruder film looks like a controlled demolition to me.”