Gaddis worked as a newspaper reporter and writer-editor for a Warsaw, Indiana, radio station from 1947 to 1952.

He then worked as a public relations writer for Studebaker-Packard Corporation and Mercedes Benz Sales in South Bend, Indiana.

[4] Gaddis' statements on the Bermuda Triangle and spontaneous human combustion have been criticized by skeptics for being inaccurate and misleading.

Gaddis has also drawn strong criticism for ignoring possible natural explanations and inventing mysteries where none exist.

[5][6][7][8] Historian William K. Powers from Livingston College, Rutgers University has described Gaddis' American Indian Myths and Mysteries as an "outrageous and intolerable book" filled with crackpot claims and "Danikenesque delusions".