From "What exactly are my obligations in a situation like this?" by Aaron Stern, in McSweeney's:
On my walk to the subway, I often pass a homeless man who stands on the corner begging for change. If I’m carrying coins or small bills, I am generally happy to give something to him. I have never seen him drink alcohol, and he doesn’t appear to be a drug user. Therefore, I’ve assumed that he has the capacity to be judicious with how he spends his donations. Then, yesterday, I saw him in line at the Whole Foods around the corner, buying a box of gluten-free muffins. Not the Whole Foods 365 brand of gluten-free muffins, but the fancy ones that cost four dollars more and frankly aren’t as good. Further, I have no reason to believe that he is in fact even gluten-intolerant. Plenty of times, I have seen him enjoying someone’s half-eaten Bahn Mi or Shake Shack burger and he seems to do just fine. As someone who thinks she possibly might have Celiac disease, is it within my ethical bounds to confront the homeless man about the legitimacy of his gluten-free lifestyle? Or should I just stop giving him money until he owns up to the lie?
— T. S., Brooklyn
More puzzling ethical quandaries can be found here.