If you give money to beggars, it just fosters begging as a viable economic option. Here in London, I get approached by beggars several times a day - sometimes two or three on the train and a couple in the street, on my way to and from work. I never ever give money. I work with former homeless people and they support my stance on this. Indeed if I meet a particularly noteworthy scammer (like the guy who cuts his own arm every single day and pretends he needs taxi money to go to hospital), my colleagues will usually know them. Here in London we have a situation where all beggars are 'professionals', simply because the competition is such that if you don't have a good story, you won't get money. I participated in a thread on this topic before and got given a hard time initially, but I won't accept criticism from people who don't live in places where they get begged from every single day. Beggars and scam artists no doubt see pilgrims as a soft touch, and they are right. Living in a little bubble of small good deeds and niceness, makes it hard for the peregrino to say no to their demands, and they know it. Beggars are also often controlled by pimps who take nearly all their money - do you think the 'deaf and dumb' girls are free to stop begging and get a job? They are probably trafficked and controlled and the money goes to criminal gangs. So sorry to break your illusions of doing good deeds, or it not really mattering.
If someone is really in trouble, you can offer them practical help, like making phone calls or buying a sandwich. The career beggar won't be interested in this, and will make excuses and a sharp exit.