Charity and compassion should not come with expectations. People who refuse a plea for help because the person asking might buy drugs or alcohol are actually saying "I can't help you in your time of need because you might not behave in a fashion acceptable to me."
Sometimes people addicted need the addictive substance simply to survive another day.
I often give money to people who obviously need help (they don't always need to ask.) I couldn't care less what they do with the money. I just hope it makes their life a little better. Actually, once I give them the money, it's theirs, not mine.
As the world changes daily, the words "There but for the grace of God go I" resound with truthfulness. If you, a caring human being, attach conditions and expectations to your charity, compassion and love, are they really such? Perhaps you are simply being judgmental. Give when you choose to give, then be thankful you're the one giving.