Section 4. No license application conforming to the requirements of sections three and three A shall be denied except after a public hearing held by the deputy director in accordance with and subject to the provisions of chapter thirty A. No such application shall be denied except upon a finding by the deputy director after said hearing of one or more of the following grounds for denial: (a) that the applicant has been convicted of a felony; (b) that the applicant has followed a continuous and flagrant course of misrepresentations or the making of false promises, through agents, advertising or otherwise, in the conduct of auctioneering or otherwise; or (c) that the applicant has failed to meet or has violated any of the requirements for licensees set forth in this chapter. Upon denial of an application, the deputy director shall surrender to the applicant the bond filed with his application within the time set forth.