Why does Gladys use the name "Cornflake Grady" when referring to Grady in the novel, Sun House?

Gladys views cornflakes as a symbol of the mass-market, consumeristic lives led by the majority of Americans. Thus, she frequently refers to Grady as "Cornflake Grady," which illustrates the life he leads while he is not traversing the peaks of the Elkmoon Mountains.