Back to the original post, I agree with those who have said it is not a requirement to acknowledge any stranger's demand, be it a panhandler asking for money, a kiosk worker yelling "Ma'am, can I ask you a question?" (which is a ploy to get you to stop so they can dump lotion on you), or those annoying people doing "surveys" at the mall (No thanks, I'm here to shop/eat/powerwalk, not to do surveys.) These people are not attempting to engage in friendly conversation, or anything else sociable. They want you for what you can give to them (money, time, etc). Also, the woman standing nearby who loudly commented on how rude YOU were .. was rude herself, and also deserving of an ignore.
Several years ago, I was returning from a store to my car with my young child and as I was putting my things into the car, a man approached and gave me a story about his family of 7 living in a van (gestured vaguely across the large parking lot) and he just needed money .. I told him honestly that I don't carry cash and he actually asked to follow me to an ATM so that I could get some out for him! Nevermind that I was a young woman alone with young child, and this "van full of family" was nowhere to be seen.
Another time I stopped to get gasoline and while the pump was running a guy walked up to me (kind of blocking me between the pump and my car), and asked if I wear _diamonds_. I had to have him repeat himself because I was sure I hadn't heard him right the first time. I said "No," and he said OK and wandered away. I noted he held a folded newspaper with gold-colored necklaces and things hanging out the back. Seems maybe he had "diamonds" to attempt to sell to me? I don't know. A fuel station employee asked me what he'd said to me and I related the story and she shook her head, saying that happens all the time here. As I got back into my car she was calling to him that he'd have to get away from the station door (where he'd taken a spot leaning on the wall), and he'd have to get off the station property (i.e. out of the lot, over by the street).
I'm sorry to say I tend to not trust beggars, because I live in a large city with numerous services to help find employment, day shelters, overnight shelters, where people can get food and shower, and maybe a bed, and even the YMCAs I think will allow someone to come shower there. I see no reason to harass lone women in parking lots, or stand on street corners with cardboard signs. They work in teams, several will sit a ways away, while one stands at the freeway exit with the sign, and they take turns.
It warms my heart to see the stories of those who pass the same apparently homeless persons regularly and exchange pleasantries with them (Hello; Thanks for holding the door; Warm weather we've been having!"), and I suspect those who are genuinely pleasant like that are more likely to be given spare change when people do have it, even if they haven't asked for it.