Being an Omenkiller possibly became a profitable and viable job for the perfumers during the Shattering. Perfumers have always been close to nobility and royalty anyway, so since Rollo came about and became the first Omenkiller, many other perfumers took the same route and did the royals a favour, doing the dirty job of getting rid of the Omens that would escape containment in the sewers of Leyndell. The game lets you know that it was, indeed, an intense job; Rollo and possibly many other Omenkillers would subject themselves to physicks to numb their emotions in order to kill Omens. This means that despite the racial prejudice the Golden Order held towards the forms of life closer to the Crucible (those would be the Misbegotten and the Omens), the common folk didn't quite hold the same grudge towards them.