These Nazi types of which you speak, are in absolutely every Hobby.
But as for costumes involved, go talk to some historical re-enactors sometime. I've been in that hobby since I was a little kid, and I have literally seen everything you could possibly imagine.
One of them crazier ones I've heard lately, with the guy who came up to my group's line of World War II vehicles at a display, declaring that he alone was the only person on the planet who knew what the actual formula for paint on World War II Vehicles was. It was really difficult to stifle my laughter, because the paint codes are public knowledge, almost everybody in the hobby has that information if they really wanted. Just mixing the paint is a real pain, so most just go with the commercial spray paints.
I did not bring my World War II Jeep to this event, but I mention to him that my vehicle was painted in the correct paint. He scoffed at the very idea, and ask how that was possible. With a smirk, I told him that the vehicle was actually painted with original World War II paint, about 20 years previously. With no more argument to make, he stood there before befuddled, and then Proclaimed that my jeep was poorly painted because the World War 2 paint didn't have the proper sealing capabilities. Mind you, he's making this declaration without ever having seen it.
I asked him what his vehicle was painted in, and he admitted he didn't own any military vehicle, and never had.
I told him to go choke himself, and walked away.
-Lee
Flickr photo set of my On30 layout