No person who engages in the practice of professional gambling on dog races, or in the practice of making gambling or wagering books on such races, or who knowingly takes any part in such practices, shall be eligible as an applicant for any license or permit to operate a racetrack or a race meeting under this subpart, or to be connected therewith in any capacity; and any association or corporation which has as an officer, director, stockholder, executive, or employs any person who engages in such practices shall likewise be ineligible as a licensee, and the commission is hereby empowered to inquire into such matters in entertaining any such applications and otherwise administering this subpart.