I grew up next to an antique store. I also had a mom who would take me and younger brothers to garage and yard sales when we were little on Saturday mornings, basically babysitting us so my older siblings had a break.
Anyway, I learned about it then. And its been a bonding thing with me and my younger brother. He made a side hustle out of it actually. We go to thrift stores in white areas because they have the best stuff. We go to thrift stores of charities. We have found some great stuff from thrift stores for breast cancer, and others. What we learned is that they have a charity dinner and a clothes donation. These are very rich white folks who donate the expensive, luxury brand clothes they got for birthdays, whatever and never really liked.
I got a pair of Cole Haan loafers once for $20, barely worn and retailed at the time for $120. It lasted years. As a kid my mom and my aunts only went to yard sales in rich zip codes. We ended up with some antique things in our house that was worth a decent amount of money. I collected coins as a little kid (Yeah, I was a nerd...ain't it obvious) and we ended up at a yard sale for a guy who was the son of an Ambassador when he was young. The dude was old, had to be in his 80s or whatever, but I got coins from Germany in the 30s that had the Nazi insignia on it as well as other countries. He spent his childhood traveling internationally. I still have those coins.