Instead of giving you money, I'll buy food, drinks.. but, cigarettes?

But it's not what they are spending their money on, it is what you are spending your money on. Without making any moral judgement on them, it is OK to say "Sorry, that doesn't work for me. Can I get you something to eat or drink instead?" So it's OK that you are freeing up money to spend on their bad habits, you just don't need to be a party to it.

The Ethicist http://www.nytimes.com/2014/05/04/magazine/brother-can-you-spare-some-emphysema.html?_r=0 dealt with this issue; it's worth a read.

I'm of the view that part of America's shocking homelessness problem is exacerbated by all the moralistic strings attached to everything that should have been a hand-up. In places I've been that don't have homelessness, the hand-up is done with money, not food-stamps, with the acknowledgment that the recipient knows their own circumstances best, and should have the freedom and dignity to make their own decisions about how to make the most of their situation. So I personally think cash without strings is best - you're not their nanny. And then you're not just giving someone something that could help, you're allowing them to exercise some respect and dignity, which for a lot of people in that situation is pretty precious in its own right. But if you've decided to offer food, then you're offering food, and you don't have to offer something else they suggest, and they don't have to take up your offer. But I think life on the street is shitty enough, and the societally-organised help on offer is already narrow and controlling.

Where's the line? Why not refuse them money because being homeless is unhealthy and they should stop being that? How about telling them you'll buy them a cheese sandwich but not turkey or roast beef? Or only gluten-free bread? What if you offered to pay for their prescription medication, but not their antidepressants? I mean, homeless people are generally accustomed to being patronized, scolded, punished, and having arbitrary conditions put on whatever help they might receive, so you're only a drop in the bucket, but if you want to treat these people like grownups who are making the best decisions they can under the circumstances (for reasons you do not know), either buy the cigarettes or make a cash exception for that one thing, giving them $5-6 for a pack of the cheap shit. Or specifically offer to buy food/drink, if that's all you're willing to buy.

For someone who is addicted and does not have any option but to either quit cold turkey or keep smoking, cigarettes may as well be food.

To offer someone a gift is to offer them something that *they* want. If you aren't comfortable giving something as a gift, you don't have to give.

What if they ask for Doritos or Twinkies, which are not good for you? Would you demur and ask what kind of fruit they would like? What if they asked for a copy of the New Yorker? There's a continuum of good and bad things they could want; if you're asking what you can buy for them, you're kind of setting yourself up here. (Although it's a very kind offer.) If you don't want to be put on the spot if a homeless person wants something you don't want to buy, how about carrying something for them, like a bag of nuts, or some powerbars, and handing that out when you see someone in need? It may not be what they'd like best, but this is literally a case of beggars can't be choosers.

Rather, I want to caution against the idea of providing cigarettes to homeless folks specifically in the name of harm reduction or mental health promotion. It may not "promote mental health" but I think it does, in fact, work as harm reduction. I strongly suspect that going through bad withdrawal on the street is not only physical torture but possibly a good way to wind up assaulted by other homeless people for being "rude" to them or arrested for some kind of socially inappropriate behavior that could be hidden behind closed doors if you have a home and are suffering withdrawal but, being on the street, you have little or no means to hide it. Middle class people almost never seem to look at what a homeless person is enduring and think "Poor guy." Instead, it gets framed in the most blame-y, "what can we arrest or banish him for?" manner. I have had some asshole in a car yell at me out of the car window "Drink too much???" when I was puking in the bushes. I do not smoke, drink, take illicit drugs or take medication of any kind (whether prescription or OTC). I have a life threatening medical condition and I sometimes lose my lunch not long after eating it. No one thinks "Poor gal with serious medical condition and look at how she is suffering." They think "Wino -- and obviously deserves to be on the street. Go die, bitch." (oh, and while they are at it, "How can I get my licks in in the nanosecond I have to interact with her?") I have built-in social support in that I am on the street with my two adult sons and I have an education (including work equivalent to graduate work) and I am generally pretty savvy about dealing with all kinds of problems. For a lot of other people on the street, I can well imagine that a free cigarette to stave off the worst of withdrawal (or suppress hunger pangs) is the difference between muddling through one more miserable day and things coming completely unraveled overnight. The optimal care your quote is promoting is very much an idealistic goal for upper class people. Most people on the street have no hope of any kind of optimal care on any front.

Oh, I will add that, as I understand it, smoking also suppresses appetite. That might be one reason some folks on the street smoke: because they can't afford to eat and it at least makes them less miserable in the face of that.