Girl Scout leader here! I run a multi-age troop in a small town and have girls from 1st grade up to HS Seniors, 19 girls total broken into smaller age-appropriate groups. We teach our girls to check every $20+ bill they get. We spend time learning about all the safety features and they practice checking bills, we even throw some prop bills in. As an extra measure of safety, we have counterfeit pens at every booth. One of our parents is in the banking industry and brings a UV light. We meet 2 times a week in the 2 months before cookie season. We focus a lot on "cookie math," interacting with the public, goal setting with what I call the "baby step" method, and designing our booths. These girls work hard to prepare and for some of them, it is their first introduction to all of these things. Their profits from these sales are what allow our girls to do all of the amazing, fun, and educational things they want to do. This year my girls have taken swim lessons, been to several Indigenous museums in our area, learned about internet safety, went to the coolest aquarium, been snowshoeing, went to spring camp, visited a library designed for kids (the loudest library I've ever been in,) wrote and performed a play about loving yourself and finding friends that accept you for you. Just to name a few. Most of our girls would never get the chance to do even one of those things, they come from toxic homes in a drug-addled town of less than 3000 people. I know the Girl Scout experience gives these girls a safe place, keeps them off the streets, and teaches them life skills they aren't going to get at home. Unethical and belongs in this sub, yes. Hurts children so it crosses the line? Also yes. Just don't.

TLDR: Girl Scouts are taught to spot fake bills, they work hard and learn a lot with the profit earned. Don't hurt kids.