In years past Fontana was often called Fontucky. The nickname Fontucky was given (and is still used today) because of the number of poor white people and rednecks living there (much like the back woods of Kentucky).
The nickname Fontucky has stuck and is still used partially because of the people living in some of the "nicer" surrounding areas such as Etiwanda and Alta Loma. People living in those areas try their best to differentiate themselves from the lower-income, lower classes and higher crime rates often associated with Fontana. By referring to Fontana as Fontucky, it perpetuates the stereotype which many claim is no longer true.
Today, the average income of Fontucky is actually slightly higher than the rest of California however the average home value is far lower than the rest of California. The lower home values of Fontana may be partially due to the number of mobile homes in the area which also makes the name Fontucky stick.
More people now refer to Fontucky as "little Mexico" or Fontalajara because the majority of people living in Fontana today are of Hispanic or Mexican descent. There are over 400% more "Mexicans" in Fontana today than there are Rednecks (aka, poor white trash).
No matter if you call it Fontana, Fontucky or Little Mexico, Fontana is still considered a shithole by most people!