What really pisses me off are those sanctimonious gits who say "Don't give them anything, they'll only spend it on booze".
Jesus (and he'd be on my side here)! Is there anyone who needs a drink more than some person down on their luck.
So, if I can afford it, and sometimes even when I can't, I try to chip in a dollar or even some loose change if that is all that I have. And if they buy a bottle and have a little consolation, then good luck to them.