Food and hygiene slander have long been the spear tip of attacks by contemptuous (or envious) Westerners seeking to make Chinese seem impossibly alien, and thus unassimilable and inadmissible to their "civilized" countries. Back at the turn of the 19th century, Chinese were commonly
regarded as "dirty, heathen rat-eaters";
vintage ads for a pest poison called "Rough on Rats"
played on this perception; also by suggesting that it was nearly as effective at controlling vermin as hungry Chinese people, while op-eds took that stereotype and expanded and elevated it to fearful, monstrous proportions, with a typical editorial in the September 29, 1854 edition of the New York Daily Tribune
calling Chinese "uncivilized, unclean, filthy beyond all conception, without any of the higher domestic or social relations; lustful and sensual in their dispositions," and warning the federal government to ban further influx of Chinese into the United States.
Spurred on by these descriptions, some took it into their own hands to reduce the number of Chinese in the country, gathering vigilante bands to burn down Chinatowns and kill their residents. One of the bloodiest
mass murders of Chinese took place right here my city of Los Angeles in 1871, as a mob of over 500 invaded the city's old Chinese quarter and slaughtered and hung 20 men, mutilating their corpses in the deadliest known single lynching incident in US history.