"She asked me to "loan" her some money so she could buy gas. I hesitated, then said, "If you follow me to the gas station and put a couple of gallons of gas in your car, I will pay for it." She turned and walked away."

I'm not a fan of being bullshitted like that. I prefer a straightforward approach. If a homeless guy asks me for a few quid which is obviously for booze or whatever (Bums seem to find me approachable in that way!) I will oblige if I have anything in my pocket. I don't judge about addictions, but junkies wearing 'pity me' wan expressions turn me off though. I'm much more likely to give to someone who asks openly for a few bob, rather than someone who's pretending to be dying of hunger - especially when they're all 'alternative lifestyle' uniformed up.