I don't believe any of it simply because I do not have the inflated ego, the audacity, or the arrogance to assume that aliens would EVER want to visit Earth. I just plain don't believe in aliens visiting our planet, plain and simple, period N-o. The chances of such a thing happening are astronomically small - so small that it should not even seriously be considered a possibility by sane people.
Then again, the people who believe in aliens, and crop circles, and how the world is going to end in 2012 (or any other year), and Nessie the Loch Ness monster, and bigfoot are the same exact people who believe Bush planted bombs in the WTC's and purposely caused 9/11. These are
all conspiracy theories, every single one of them, and their strength lies ONLY in the fact that you can never 100% prove they are NOT true. Doesn't mean they aren't a bunch of hooey - they are. But if you can't absolutely prove them wrong, then a small part of the population will still believe, even flying in the face of logic. Elvis is still alive, the pyramids were built by aliens, and Kennedy was shot by someone on the grassy knoll.