My Speckled racer also can leave nasty bites, but its easily explained without getting into saliva or Dunevoys glands etc. With a microscope, the backside of their teeth are sharp-edged and serrated like a bread-knife! They're not rear-fanged, as you guessed. Due to the teeth, his being hyper as are most racers and as a possible prevention of spreading disease, I always use a pair of those very thin surgeon's rubber gloves when handling this guy. Apparently the taste or texture is awful, because none of my animals (even a hungry adult Pine snake!) will bite more than once when I'm wearing these. The racer's tamed down considerably from two years ago, eats hopper mice ravenously but he's still a wild-caught, and a racer.... can't expect cornsnake behaviors, I guess.