every city you mentioned has its good and bad area's
I am just here wondering how rich OP is considering he is thinking about buying real estate properties in different countries. Usually people tend to just buy real estate properties in their own country. Probably for easier maintenance and surveillance.
It also helps that you are most likely to be aware and understand of the laws and everything legal matters in your own country where you are a citizen of. I am sure there are some peculiarities when you buy assets in a country you are not a citizen of and that sounds like extra work.
its not just that he pretends he ha a dream to buy property in other countries (though sounds like a scam) . but lets pretend he was genuine..
so imagine he done one of them online auctions to buy a property.. he has no clue the condition of the building and would need to pay for renovation costs and such. then a management company to manage tenancies and also all the local government property tax stuff
without knowing anything he cannot even dream of profit without knowing the basics