Cityjet on occasion have an IAA inspector flying with them. However an incident involving this person is revealing.
Said person was sick on the flight and absented herself from the flight deck for the approach. Such is the life. However:
Captain in question (a senior training capt) continued the approach, made no mayday call or otherwise informed ATC of the situation and landed in CDG. Apart from the poor airmanship in not notifying that the flight was operating under severely degraded conditions, no calls made is in total contravention of the ops manual.
The result: captain shortly promoted to check captain. Not a word from the IAA. No incident report, no investigation, no nothing.
You can decide for yourself how effective IAA auditing is if this is the outcome when the IAA are on hand to personally view the cock-up.