where did the dollar really go?

i gave a woman next to the metro a dollar today. normally i don't do that, but for various reasons i was feeling particularly altruistic, so when i walked out of the metro and onto the street and she was standing there asking for 50 cents to get somewhere, it was hard for me to resist. coins i had not - so a dollar it was.
as i walked away, i turned to see if she had gone down into the metro system - the dollar i gave her was more than enough for her to catch a train to anywhere she needed to go. but she was standing there still, approaching others as they came out of the station, asking for more. and my heart just sank.

the reason i normally don't give money when asked in situations like that [on my commute, as i walk around the city, etc.] is because past experiences have taught me that what people request is not truly what they want. "i need 50 cents to get to bethesda" is fine; using the money otherwise is just, well, depressing. to me, that is - as the giver. i'm not sure what drove me to feel that today might be different, in all honesty.

but in any case, this small case of 'abusing aid' led me to think about the ever-growing concentric circles in which this happens. we give aid to foreign governments: how do we know, initially, who will use that money efficiently for the good of the nation, and who will siphon off large chunks for personal gain? we give criminals a second chance: how can we tell who will remain law-abiding, and who will return to a life of crime?

some argue that in order to make up for the dishonesty of some, leniency should be kept from all. but is that fair? are all individuals/organizations/governments corrupt? of course not. but i know that at a certain point, cynicism builds up - - hence my tendency to avoid giving money to strangers asking for subway fare - and likewise, i suppose, reluctance for taxpayers to subsidize international [and even domestic] aid.

so what's the solution? do we subject people/organizations/countries to ever more stringent rules and tests? do we give up on them altogether, letting the strongest survive while others fall by the wayside? do we give aid to all, hoping that most are honest and that feeling good about those who are will be enough to mitigate the immense feelings of disappointment over those who are not?

i know, countless volumes have probably been written on this. but in truth? i just want to know what to do when someone asks me for money on the metro. i hate the fact that i'm such a cynic. and yet, life seems to indicate that without the cynicism creating a thick skin, all i'm really doing is setting myself up for disappointment.