What Else Could I Do?

I'm sitting at the far end of an empty strip mall parking lot waiting to meet my parents. A woman in an old beater of a van pulls up alongside of me and honks. I look over, an infant carrier is perched on the seat next to her with a small, grubby baby facing my way. As I roll down my window, I know what's coming.

Her: "Can you give me gas money to get to a shelter?"
Me: "Sounds like you're trying to scam me."
Her: "I'm not. I'm trying to get to the [Name of Shelter for Battered Women]."

I take a moment to ponder the situation. I can tell by looking at her she's not from the immediate area. She's also nowhere near the city the shelter is in. I'm 99% sure she's a scammer. But what if she isn't and she really is trying to get to a shelter? What the hell.
Me: "I'm giving you five dollars, and if you're scamming me I'll let it be on your conscience. If you're not I wish you luck."
As I hand her the money she breaks eye contact and looks down. At that moment, I know I've been taken.

I don't feel bad about it. She probably isn't familiar with the word, "conscience," and I can afford the five bucks. And there is still the eensiest chance she really was trying to get to a shelter. I'd make the same decision next time.