I don't judge. If I spare money, I will give it - if not I will not.
It is not up to me what a homeless person does with the donated money - Obviously I would rather they buy food, but if they are addicted to drugs, going cold turkey can be just as lethal as not eating.
I do lots of work with a local homeless charity, handing out care packages and the like. Even the people "conning" the system are never as well off as we assume.