A thank you to Ms. Gundula Tutt, who sent me this message:
there in fact IS a connection between the 190SL and prostitutes in the 1950s:
Germany's "most well-known woman of loose morals" at that time, Rosemarie Nitribitt, owned a black 190 SL. Together with it's prominent female driver and her poodle, the car back then was talk of the town in Frankfurt am Main and the whole country. Rosemarie Nitribitt, practised her profession quite openly and displayed a very eccentric, luxurious lifestyle in public (including her beautiful car). She found her clients in the high society like politicians or managers and was some kind of "living scandal" in prudent post-war Germany, until she was killed under mysterious conditions in 1957. This case has never been solved and ads even more drama to the life of this enigmatic woman. The story later served as basis for two motion pictures...."
Rosemarie Nitribitt (1933-1957). One of her customers gave her a used Opel Kapitan as a present, and later using her own money she bought a black 190 Sl roadster, which colloquially would be referred to as the Nitribitt-Mercedes. Police later estimated later that in 1956 she earned about 80,000 DM.