Personally, I think that I should not give money to beggars.
First of all, there are a lot of professional beggars that are richer than an average citizen. I remember one beggar who was always begging at a Metro station I used often. Then I saw him driving alone while he passed me in a cool car and was well dressed. That angered me greatly when I saw him begging back in the Metro after seeing him in his car.
Second, some beggars are just drunkards who don’t want to work. They prefer begging to working. If you give them some money you encourage their idleness. Once, I saw a man who begged in the morning and by my lunch time was drunk on the sidewalk.
So, that’s why I don’t give money to beggars.