Hi, I'm a white female 59 year-old New Age eclectic neopagan.
I once purchased some copal and took it home and burned it. It had no spiritual effect; all it did was fill my apartment with smoke, so I never bought any more. Later, I purchased an anthropological study of some Mayan Indians in the highlands of Guatemala. The author really did live with these Indians, learn their language, and was trained by one of them as a day-keeper (a type of indigenous religious specialist). One of the things I remember vividly from the book is how often the people were burning copal in the communal fire. This book brought these people to life for me, and now I feel creepy about having used copal. It's a sacred resin from Guatemala. I shouldn't use it.
Unfortunately, other Indians are still shadows to me, so I don't have this impression about other sacred objects. (Wait, this could change. I just had "The Sacred" handed to me. It says on the cover that it "offers an uncommonly wide-ranging consideration of the ways in which Native Americans view the world, their place in it, and their responsibilities to it." So far, it doesn't sound plastic, although "wide-ranging" seems problematic. There's a lot of tribes out there.)
Vine Doloris Jr. devoted a lot of words in his book "Custer Died for Your Sins" (What, is it wrong to buy books? Why does Mr. Doloris write?) to the proposition that anthropologists are either foolish or evil. I disagree with him. Some anthropologists are foolish or evil, but others make people real.