I've lived in downtown San Diego for a while, and I've taken to just getting to know some of the homeless people who hang around the 7-11 by my apartment and buying food for them when they ask me.
That being said, you did a good thing by trying :)
With a taste like that in food, I'm not surprised your latte and (excellent, I'm sure) Starbucks sandwich fell on stony ground.
Good sentiment though. May karma follow you throughout the day.