The wife and I just got back from a trip to Italy and Greece a few weeks ago. In Italy wherever we went we were constantly accosted by black people, all men, trying to sell us various things.....watches, water, umbrellas, jewelry....they were everywhere.
My wife actually did buy an umbrella from one of them for five euros. One person in our tour group bought one, and it stopped functioning shortly later. Our tour guide warned us about buying supposedly expensive stuff from the hawkers, but some people still bought things.
I never saw one hawker who looked like a native Italian trying to sell us stuff on the street.
Even if you were wearing a rain coat or had an umbrella, they'd try to sell you another one.
When we got to Greece, we didn't see any of these people. Greece is either not a desired destination like Italy for the Africans or Greece has a much tougher immigration policy.