I don't, but it's because I hardly ever have any actual cash on me. Our small city does have a homeless shelter and several food panties accessible by walking or bus, so I don't feel *too* bad if can't/don't give them any money - there are resources that can help. My small city is home to one of the state mental hospitals so we have a surprising number of homeless for a city of only 120k people, many get released and have no place to go, so they hang around the downtown and immediate neighborhoods. I do give to the food pantry and the homeless shelter around the holidays, it's actually a line item in my YNAB!
DH will give to anyone that asks him for money, no questions asked. Long before DH and I met, DH actually *was* homeless for about 6 months when he was in between jobs in his 20's. DH also told me a story about when he worked for a finger-lickin'-good fast food fried chicken chain. At the end of the night, they had to toss any already un-purchased cooked food out into the dumpster. They generally just carried the trays full food and dumped them right in. One night after closing the store, DH noticed that some homeless guys were dumpster diving for the food, apparently they'd wait for it to get tossed then go in after it once the employee went back inside the store (remember, this is just un-wrapped food thrown directly into a dirty dumpster).
DH asked his boss if they could just give the food to the homeless guys at the end of the night. Boss said "no". (In fairness, this could have been due to liability reasons, or just not wanting to attract even more homeless people to the store late at night which can cause problems of its own, the boss wasn't necessarily just being a jerk). So whenever DH could get away with it, he'd box up the food as if it were being given to a paying customer, and he carefully placed it all on top of the dumpster, so the guys could at least get clean food. DH figured anyone willing to dig their dinner out of a dumpster probably legit needed the food.
Another story I like to tell when this subject comes up is this one. Many years ago, a friend of mine badly hurt her leg and had it in an enormous brace, and walked with crutches (it was like this for months on end). She was in college and lived at school in downtown Chicago during the week in the dorms, and took the train home on the weekends to her mom's house out in the far suburbs. The commuter rail in Chicago all goes in/out of Union Station, where there are a semi-permanent collection of homeless people who call the station home base.
One Monday morning, she was getting off the train and making her way through the station along with the rest of the huge morning rush of train commuters, when she tripped and fell flat on her face - crutches, purse, and book bags flying everywhere. All the other commuters just kept right on walking around her, totally ignoring her. A couple of homeless guys where nearby and saw her fall, and came over. At first she was afraid they were going to take her dropped bags and take off. But they picked her up, dusted her off, asked if she was ok, and gathered up her crutches and things. She thanked them profusely and headed off to school, as she still had a ways to go and she didn't move too fast on the crutches, and didn't want to be late for her morning classes.
The following Friday, she was back at the station heading home for the weekend, and saw the same group of homeless guys. She went into the McD's at the station and bought several super-sized value meals and walked over to them. She thanked them again for helping her and gave them the food, for which they were quite thankful. She loves telling this story (and I love sharing it) because it was the well-off commuters where the ones to ignore a young lady clearly in need of some help, and t was the homeless "bums" who stepped up and did the right thing. Those homeless guys were likely homeless for all the reasons stated in this thread, addiction, alcoholism, mental illness, etc. They were still more decent than the "upstanding" citizens were that day.