[A Goofy Family]

I wouldn't mind at all either! Maybe strike up a conversation with a family on the bus or monorail, see if they've ever pin traded and offer a pin or 2 to start them out. Depending on the child's age, they'll remember it forever.
A few years ago a lady in Epcot stopped my daughter (then about 9 or 10yo) and asked to trade a pin. DD was hesitant (it was a set she was trying to complete), but the lady explained it was her last day in the parks & she only needed one more pin to complete her set and would trade any 2 off her lanyard for DD's one. She got a couple of really cool pins and still remembers the story to this day...and the pins she traded for. BTW...she completed her set by trip end.
The kids also remember special CM's randomly giving them pins. So your actions will be long remembered too I'm sure! What a sweet way to spread the magic!