Churches, etc, are targeted by the very people you describe.
I've got a bro in law who used to volunteer delivering food to "needy" families using his business's trucks. He became very disenchanted with the whole thing after one Christmas where after delivering many boxes of food to "needy" people, they got very little thanks. He remembers personally toting in many boxes of food to one woman and her family.
The woman wordlessly pointed to where she wanted the delivery people to put the boxes of food and clothing. After they completed the task, the woman simply pointed to the door without saying one word of thanks. That was the last Christmas my bro in law volunteered to do the charity thing.