I worked at homeless places and volunteered at a soup / sandwich place for the homeless for a long time. I also lived amongst areas that were quite deprived.
Not all homeless are obviously homeless.
Not all addicts are homeless. Lots of addicts can keep a job and keep the addiction secret.
Lots of addictions are not obvious.
Some things seem like they should be illegal and considered sinful by the standard of harm they cause - but are acceptable (like junk food - the amount of christian talk I hear about the harmfulness of homosexuality and the free pass junk food gets - it's absurd to listen to - but I digress)
I think the OP is talking about someone who is obviously homeless and obviously an addict.
I don't give money, nor do I buy food anymore either.
I make eye contact, listen to the person speak, let the person finish their sentence. I don't rush, I stop and make a deliberate effort to treat as an equal / as a human being.
Treating people well is the best thing you can do for them. This is (for me) the second basic standard in christianity. (First is love God, next - Love people - lots will disagree with that and think christianity is about being saved or something else. To me I think it's about Loving God and Loving People).
I don't volunteer anymore because, although, mostly, people were good,
occasionally, I would get treated like dirt by some of the guests - physical aggression / verbal aggression - one bloke slammed his coffee on the ground and it went all over me. I got fed up with stuff like that happening (albeit occasionally - but often enough to remember) and stopped volunteering.
The reason I didn't go back after cooling off period is that I didn't see giving out free food to people, who wanted it, as really all that loving. I figured I had been factored into their plans to get a free dinner and they had other plans figured out to acquire drugs. I felt I had ticked a box by "feeding the poor" and they had ticked a box of getting food that allowed them to keep their heads above water on the drug front (one less thing to worry about).
I figured to really love people, it's a lifelong commitment that must be sincere friendship / relationship.
Lots of times I brought food, the person I bought food for just treated me like an object - like a lamp or a tool that was there to solve a problem of there's.
I'd like to refocus working for God - but instead of giving food - give in relationship - build people up. (Teaching someone how to cook).