Hi brother,
I have often wished that I could give money to more people who are suffering. If I had a billion dollars, oh what a difference I could make! But that is not how God has set things up. His plan is for there to be a lot of suffering in this life, and I don't think it will ever end with any amount of human aid. There have been innumerable campaigns with the stated goal of ending hunger or poverty or drug use or whatever. They all fail, because Unless the LORD builds the house, They labor in vain who build it (Ps. 127:1). Jesus said "The poor you will always have with you" (Matt. 26:11), and the Law of Moses said the same thing (Deut. 15:11). It hurts to think of all the people who are suffering, but there's going to be suffering until the return of the King.
I say this not to discourage you from giving (the same passage which says the poor will always be here also encourages generous giving--Deut. 15:10-11)--but to remind you that we can't give to everyone who asks, so you don't have to agonize over this if you choose not to give. If you drove around Springfield, Missouri for a couple hours and gave to everyone who was "homeless" and asking for help, you'd have no money left. I used to enjoy giving money to homeless people (it made me feel "righteous"), but I rarely do it anymore, because of all the phonies out there. There are many genuine cases, of course, but asking for handouts is a racket, and people can make a living out of it. Ugly as the idea may be, Dennis is right to question the legitimacy of this campaign. The racketeers aren't just standing at the highway exits; they know how to use computers too.
You were personally asked in private to contribute, but keep in mind the guy probably asked all of his other acquaintances, privately and/or publicly, to contribute. People who know them better are contributing, so Julie's War Against Homelessness is not going to be won or lost based on whether you give or not.
Give if you want to, and the Lord bless you for it, but don't feel guilty if you don't.