My two cents? I think there is an unfortunate convergence going on-tourists who come from cold climates(in terms of temperature and social life) and they WANT to make friends and feel happy when they are approached.
Some of these scammers see this and take advantage, then pat themselves on the back for being such master manipulators.
This is very true. Take life in NA and walking down the street or getting a coffee and if you say hello a bit too 'friendly' you get a look.
I also know this is true by personal experience. Thinking some of the Dominicanos were really nice and good to talk to since I was learning Spanish but after returning a few times when I see who I really was talking to - wow how embarrassing.
At first it feels great to have a new friend but that feeling wears off pretty quick when the second question they ask you is either for a beer, cigarette, money, or whatever. This is a chopo no?