As for the auditors, they don't even know how to audit in the first place, or is it right to say that exchanges just know how to get smarter than auditors?
Top exchanges will definitely have issues in whatever form they are and because they are well-known they will definitely get more attention from regulators than small exchanges, with all the issues they have they are still more worthy of trust than small exchanges, if big exchanges cannot be trusted then small exchanges more untrested.