Back in the 1930s, before everyone had telephones or email addresses for salespeople, Jehovah’s Witnesses, Mormons, or penis enlarging spammers to annoy us, pests had to go door to door. Undoubtedly, this improved the cardio-vascular health of all involved. Walking neighbourhood after neighbourhood trying to catch a sucker would be keep your weight down and the occasional sprint by both parties as a very disgruntled homeowner got physical would aid in aerobic exercise.
Just as caller-id and spam guards have helped us in modern times to cut down on unwanted pitches, the 1930s had their own innovations.
Notice in the ad that the ‘housewife’ gives her extra money to charity, while ‘movie stars’ add it to their income.
For some reason, knocking just wouldn’t work.