Contamination-free anthropology is mythological in itself,* It's
  a science yet at the same time, to simply have communication
  take _place_ means there's some kind of contamination. To
  interpret WITHOUT visual presence is contamination because we'll
  be taking a series of assumptions with us into it without
  subjective input from the observed, contaminating the results
  with our bias, however proper they are from our perspective. My
  point is: Anthropology is not a lab-friendly field. What might
  be considered contamination-free in 1920 anthropology or in 2016
  anthropology might be considered disasterously contaminating in
  year 2800AD Anthropology as we presumably learn more about the
  effects of our actions upon environments. So, we work with
  simplifications and do the best that can be done. The trouble
  is, simplifications of belief constructs is not an easy task if
  one wants to do it properly. Anthropology frequently
  misrepresents a people for whatever
their reasons. That happens
  in other people fields as well. Sociology, statistics, anything
  that takes people and groups them together, and stereotypes
  their thinking together, runs to strong risk of
  misrepresentation. And - that's just within the fields
  themselves. For people OUTSIDE of the fields (not in a science)
  or in other fields, I suspect they just don't bother with
  questioning the methodologies used. And, increasingly many
  people just lump all of it together into a big ball and toss it
  in the trash into "Not Applicable" Or get on campaigns to remove
  religious things without a proper cost/benefit analysis,
  focusing on the hyperbole and drama and getting what I consider
  'political' about it all. In any case, I strayed from the OP but
  my main point is contamination is unavoidable. Scrutiny of one's
  own bias is critical.