The phrase "cotton pickers" historically refers to people who worked in the fields picking cotton. However, it can also be used as a derogatory term to insult or belittle someone. Full definition
After seeing his father (David Banner) shot dead for objecting to the land's owner (Alex Pettyfer) having his way with Cecil's mother (Mariah Carey), young Cecil gets upgraded from cotton picker to house servant. (dvdizzy.com)
Just as impressive in a smaller role is the relatively unknown Kenyan actress, Lupita Nyong «o, who plays Patsey, Epps» pet «property», who is not only the best cotton picker on the land, but also has the affection, for better or worse, of Epps, to the point where his jealous wife (Paulson, Game Change) commits her own wicked acts against her. (qwipster.net)
Dorothea Lange Migratory Cotton Picker, Eloy, Arizona, 1940 Lange's work from the permanent collection at Oakland Museum. (lssartadvisory.com)