This is very true. I studied Nazi and Soviet use of archaeology as a propaganda tool for my unfinished (I cut it short and got an MPhil instead) PhD. I'm also, as I said the other day, fascinated by British deception during WWII. Two major things about propaganda occur to me (and are widely held to be true). Its easy to sell a lie if: 1. It confirms what people already believe (or want to believe) 2. It is based on a manipulated version of the truth. These Led By Donkeys videos are excellent examples of propaganda, presenting what is undoubtedly fact but with the context judiciously used to bolster their argument or through the use of fact that is irrelevant but hints at things (such as nepotism) that are distasteful to the public.