Green’s Dictionary of Slang

a pimp who prefers charm and persuasion to threats and violence when dealing with his women.

1972		Milner & Milner Black Players 35: A pimp who uses a great deal of charm and little violence or fear is called a sweet Mack or sugar pimp. One who uses brutality and threats is a gorilla pimp or hard Mack. [Ibid.] 230: Most players say, ‘You must hate to be a pimp,’ even a sweet pimp.
1977		J.L. Dillard Lex. Black Eng. 87: The pimp who does not exhibit the Iceberg Slim-type dominance [...] can either be a sweet Mack or a sugar pimp.