I realize this is an old thread, but it occurs to me that one of the problems is that implausible conspiracies are lumped together with plausible, likely operations and dismissed as a group with a single label.
Apparently the CIA popularized the term 'conspiracy theory,' in the 60s, though I don't have knowledge on the veracity of that claim. It's clear that at least a non-pejorative term would be useful.
