What scams or deceptive things have you experienced?

The year before last, I traveled to Beijing alone. While waiting for the bus at the train station, a little girl held up a sign that said, "Please do your part to care for deaf-mute children." Seeing that the girl really can't talk, I gave her ten dollars. Not long after the girl left, another girl of the same age came, the same brand, and I gave her another ten dollars. But then another one came, and I realized it was wrong. They stare at me for money? I just realized that these children are all liars, and there are adults behind them.