i tried that once outside a boston market restaurant..some homeless lady was there...i bought her a plate of grub..and she told me to fuck off--she'd rather have the money.
That's because she can buy whatever she wants with the money...alcohol and/or drugs.
This is also the very reason I don't ever give homeless people any money. Because you know that they won't better themselves, or for the most part even attempt it.
On a side note, I was once at a truck stop in the middle of BFE, and there was a guy outside obviously homeless. This lady went into the store without asking him what he would like to eat, actually she didn't even speak to him at all- just purchased some beef jerky for him to be a good Samaritan. He comes out and hands him the package, and he's extremely grateful, but also apologetic that he cannot not eat any of the beef jerky because he had no teeth! He stated "My dog eats better than I do! Everyone at truck stops seems to buy the beef jerky for me, but since I have no way to eat it, I have to give it to my dog."
The lady silently went back inside and bought him something that he could eat.