To be fair, finding no evidence is not the same as saying Auburn is innocent. Maybe they just couldn't prove anything. If you do it right with a attorney middle man to be able to claim attorney-client privilege (the way Orgeron allegedly has done it,) there is no proof.
Clay Travis was right when he said that $180,000 investment was the best in sports in a long time. The NCAA knows they took the money, they just can't prove it. You wouldn't ask Mississippi St. for a large amount of money then suddenly decide to play at Auburn for free.
Second lesson, pay with cash and leave no money trail, don't incriminate yourself over the phone, you never know who's recording it.