Well, there was also the whole "family curse" angle
which was maybe just one big red herring but one could also use it to criticize Romero for "cheating" if he truly didn't believe that Martin was in fact a vampire. I mean, Martin's granduncle obviously believed it (and says at the beginning that there are a few other vampire relatives besides Martin who are still living). So yeah, maybe he is just a "screwed up kid" but if so, his family's at least partly to blame for that.
Ah the good ol' days of white guys smudging their faces to play spics and injuns...