I guess the question becomes, Why did they choose Auburn?
It will certainly be on a case by case basis but if it is discovered that Auburn was paying a player or multiple players will anyone ever be certain that any individual player wasn't getting paid or had gotten paid.
I personally would not want to take the risk of taking a player from Auburn then a year later finding out that player had gotten payments from a booster while at Auburn. Hate it for the kids that are clean but this is a case where in my opinion one bad apple ruins the bunch.