Are photoresistors reliable for light sensing applications?
How to deal with highly variable components? Pick one or more:


tune each device manually
restrict your problem domain to fit within the available tolerance of the components
tune each device automatically (e.g. a circuit built into your device which finds the light-dark range of the photoresistor automatically and saves the result somewhere)
sort devices to fit your problem domain


The best results will happen when you hit the sweet spot of the device working correctly for all inputs with a minimum of labor and parts.