An automatic playing card shuffler incorporating means for detecting marked cards. One or more light spectrum emitters or variable light spectrum illuminators transmit light at frequencies/wavelengths which is reflected off card backs through one or more spectrum filters causing invisible markings to become visible. A camera may capture images of the now visible markings. A camera and software collaborate to capture images and analyze the same for markings on the card backs such as smudges, nicks and scuffs and edge demarcations. The automatic playing card shufflers are configured to not only detect marked cards but to detect patterns relative to the card markings. The automatic card shufflers are communicatively linked with a casino management system and/or security system such that casino personnel may be alerted in real time to the discovery of marked cards.