grassroots sales; door-to-door marketing
Refers to persistent, on-the-ground sales activities where salespeople visit many small businesses or households, often likened to walking along ditch covers (ドブ板) in older shopping districts. Conveys a gritty, hands-on approach.
See also: ドブ板
New employees first do grassroots sales, visiting local shops one by one.
His experience in door-to-door marketing sharpened his sales skills.