Egg candling methods and apparatus are provided wherein the optical path between a light source and light detector is monitored for obscuring debris and/or malfunctions. A method of candling eggs includes illuminating an egg with light from a light source receiving light passing through the egg at a light detector generating an output signal that corresponds to light received at the light detector for the egg and analyzing the output signal to determine whether the optical path between the light source and light detector has been altered. In response to determining that a respective optical path has been altered, the light source and/or light detector is cleaned and/or inspected for malfunctions. Cleaning the light source and/or light detector may include wiping a surface of the light source and/or light detector and/or spraying a surface of the light source and/or light detector with a fluid.
