Re-enactors use the term "farb" to describe peers who aren’t being authentic in dress or behavior.
For the most part, hobbyists I saw at Atlanta looked every bit the person they portrayed. Attention to detail is impressive. A few would put away a soft drink or prepackaged food if the items were seen by spectators.
The origin of the word "farb" (and the derivative adjective "farby") is unknown, though it appears to date to early centennial reenactments in 1960 or 1961. An alternative definition is "Far Be it for me to question/criticize" or "Fast And Researchless Buying.”
It’s a tough balance: Being historically “correct” while living in a very different world in 2009.