Well conspiracies DO exist and many have been exposed. Until they are exposed of course, they are just conspiracy theories and many of them probably are not true. If they turn out to be true, they are either called a "scandal" and someone has to resign (e.g. "Iran Contra", "Gladio - NATOs secret armies in Europe") or for some reason folders with evidence mysteriously disappear (
as happened in the case of the involvement of the governmental agency in Germany that was involved in supporting neonazi groups). I am sure however that for every case that comes to light, there is at least another that remains secret for now. So I would not discredit the idea of actual conspiracies happening at all. Of course the more it takes to keep up that conspiracy, the less likely it becomes (e.g. that whole "free energy" thing). The interesting thing is that one of the main "weapons" of any conspiracy is that it is possible to make anyone who claims to know about it can be discredited as a stupid "conspiracy theorist" and not believed. Especially in the US, where there seems to be a whole culture about conspiracy theorism which basically ran out of control and nowadays even valid claims to a conspiracy are seen as dubious while other conspiracy ideas are given more credit than they deserve (the whole "climate change deniers" issue)