Konceptual99: They rely on the lack of research done by the vast majority to allow the potentially embarrassing editing of the original quote and it's context to slip by unnoticed.
Yes, sadly, 99% of witnesses WILL NOT look for the actual quote from the original source if it has been quoted in the society's material! They will just take it as factual and correct BECAUSE it is in the material.
The other 5% who DO research the original, end up on forums like this with us!