In fundamentalist parlance, the word worldly nearly always refers to matters of fashion and entertainment. It involves how a person dresses; what sort of places he goes; and the things he reads, views, or listens to. Consequently, many feel that if they just stay away from certain things, they are safe from worldliness.
In some cases, the attitude goes a step further. “As long as I have the proper appearance, never go to the proscribed places, or take in the proscribed materials, I am not only free of worldliness but also basically a good Christian.” Externals-focused preaching and institutional rules  reinforce the attitude, and plain human laziness gives it a cozy home. For many fundamentalists, avoiding the “worldly fashions and entertainments” list is easy. They grew up with the list, have never lived any other way, and never spend time with anyone who lives differently.