When he graduated, Felt took a position at the Federal Trade Commission but didn't like the work. His first case was whether a toilet paper brand called "Red Cross" was misleading consumers into thinking it was endorsed by the American Red Cross. Felt wrote in his memoir: "My research, which required days of travel and hundreds of interviews, produced two definite conclusions: Most people did use toilet paper. Most people did not appreciate being asked about it. That was when I started looking for other employment."

Felt, W. Mark. The FBI Pyramid: From the Inside. New York: G.P. Putnam's Sons, 1979. (ISBN 0399119043).