Yeah... well it started being a problem with food trades because children who were too young, didn't know, or didn't care would trade their pbj with someone elses chocolate pudding and all of the sudden you had too allergy attacks on your hands cuz pbj's mom didn't give him the pudding for a reason and vice versa... Then, when pokemon cards became a big deal parents would get irate because their child traded a really rare card for a not so rare card because it was pretty meanwhile mom was hoping to use that card to pay for college. IMO those kids shouldn't have had access to those cards if mom was gonna be so touchy about it. I was never allowed to play with our 300 year old china just cuz it's pretty. Heck, I'm still not allowed to touch it. My mom knows to keep valuable things out of her children's hands because you never know what will happen...
ANYway my kids know now not to trade in front of me cuz I'll always make them trade back.