Padi professionals are expelled and/or de-certified primarily for violation of standards, failure to cooperate with a PADI investigation, failure to maintain current certification, and of course, failure to pay dues. I find PADI to be active in following up with complaints about instructors and DM's and when an incident report is filed. If problems cannot be corrected, violating professionals are removed. The de-certification or suspension or expulsion is published in their periodical.
DivemasterDennis