The problem of beggars is not unique to Brazil, in fact we have the same problem in many cities in the United States.
While I will not deny that there are many people who need our help, there are also many who are professional beggars, and at least in Pensacola Florida, they are organized. A man or woman will "work" one street corner for a few days and then disappear for a week or more, returning for a few days at a later time. If one is observant you can determine the pattern that the beggars use to work the more lucerative corners as they move around the city, this is an attempt to avoid over exposure. Most of them carry hand made signs saying "Homeless Anything Helps God Bless", or "Homeless Vet(eran) Anything Helps God Bless".
One day about a year ago I saw a different sign which read "Homeless Vet, Hungry, Will Work For Food". Well I had some yard work that I needed help with so I stopped and offered the man US $20.00 plus a meal for a couple of hours work. He replied, "Sorry man I can not afford that, I'll make more just standing here". Later that same day I saw the same man walk across the street to a Wal Mart parking lot, get into a very nice late model Toyota (newer and nicer than my car) and drive away.
Needless to say I do not give money to beggars, and believe in the addage "Give a man a hand up, not a hand out".