A lot of it comes from left-wing "Bush is Hitler" nutcakes, but I believe things are going on that Bush doesn't know about, and a lot of things when on during the Clinton years.
Clinton had 8 years to pack the military and intelligence with all sorts of bad people, and many of them are still there.
There's some kind of video that I have never seen but the anarchists swear by that says top Republicans are doing all this child kidnapping-slavery-sex abuse stuff.