If someone begs for money telling me they haven't eaten I will always go into a restaurant and buy them a carry out meal and hand it to them. Almost invariably they throw the food away (a few will shrug and eat it)and I had one guy cuss me out big time before he threw the meal in the street saying, "I don't want *&%%** food! I want money!" I've pretty much given up.
I've found this to be the case many times too... most homeless aren't down on their luck. They are wino's or addicts or I'v heard of some that literally make a living pan handling then live out in the burbs, odd. The percentage of people that are REALLY down on their luck is minute and there are definitely social programs for them and they know.