I dont buy it. There is no way to tell a scrapper from a fake unless you have something to compare it to or it is a really bad scrapper (the rough edges as some mentioned, part of the pin not painted right, etc. I saw one of snow white and her hand was green, so that is obviously a fake).
This is not the best pic, but it is a prime example of what I am talking about. All of these pins have the exact same quality (backs are the same, font is raised the same height, no rough edges, etc). Yet I have two blue and 2 purple. Which are the scrappers? I still don't know, so I kept them all. I went online to see and it is hard to determine color shade when looking at a picture on a monitor. Every single one of them came from a cast lanyard, btw.
Honestly though, I don't care if they are all scrappers. Despite what some crazy people think. They have no value. Its not like 20 years from now someone is going to buy my pin collection. They hang on the wall in my nursery. The fun and "value" in them was collecting and hunting for each one in the set and the WDW trip where I got them. One day they will go in a box and be forgotten.
I also really doubt they can police the scrappers.
Think about it.. Is a CM really going to refuse to trade with a little 3 or 4 year old girl all decked out in her princess costume??
Also I can see all the complaints...

"I just got this pin from the CM over there, and now your telling me I can trade it to you??"
"How was I to know its a fake?"
" how is my child to know it was a fake?"
It's opens disney up to WAY to much bad press.
My family have been trading for years.. In fact my sister and attended the "classes" they had at DL for kids.
After many years of trading here are my tips...

The way my family trades:
1. We have a small pin bag. (About the size of an iPad mini.)
holds about 75 pins (25 each page)
After years of holding 3-4 lanyards why everyone went on rides. A "family" Bag makes more since
2. At home The kids go through their pins and give me all their traders
The rest stay at home..
3. 90% of the time we trade with CM.. Any pins my kids really want to keep, go into a small ziplock I keep in our backpack.
Every now and again little kids will see us trading and ask to trade too.
We always let them pick whatever they want out of our pin traders bag and accept any pin they give us.
I can always trade it to a CM later..
----I'm sorry I'm not as cold as some

. I can not tell a child thier pin is a scrapper and won't trade them our nice cinderella pin. I really don't see a CM doing that either!
I had soooo many parents look at me and say "are you sure?" Just in amazement that we would even trade.
The
------------------------- little feel good story ---------------
One time in Epcot a little girl wanted a pin I knew for a fact was a $15-$20 pin. She wants to trade us one of those bowling pins.

I looked at her and said " I just happen to need one of these, and would be more than happy to trade with you." The mother started crying & said, "it was the pin the little girl wanted in the store, but they didn't have the money to spare for such a pricey pin."
As the mother & daughter walked away A higher up CM ask us to wait a few min. He walk out with a lanyard full of limits edition pins and let us pick two.. In trade for that bowling pin one the little girl had given us!
I almost fainted.

. When I saw He had two Large mr toad pins.
so you know what scrapper or not If it makes a child happy, who cares?!?