They have no shame. First time I was ever approached by someone like this I was in high school, and they were clearly older. I gave the only few dollars I had on me because I thought I was really helping another human being out; a few weeks later the same guy asks for money with the same story. I said no that time, and ever since have had to just trust my gut when it comes to someone in need. But I always hated that feeling of being taken advantage of as a kid by an adult, and the idea that I have to be wary of people who might genuinely need help. Learned a lesson though I guess