User blog:Experimental587/Appropriate Characters are Corrupted by Profanity

Some characters (that are similar to Rainbow Dash, Lizbeth, Dib, and Eddy) is only used words that are appropriate or used slang words.

But in some stories, some appropriate characters used profanity and bad language.

Here's the examples:
What are the reasons why do those appropriate characters swears in the most of the stories?
 * 1) Lizbeth used blesphemy and bathroom humor.
 * 2) Rainbow Dash used bathroom humor.
 * 3) Skipper used sexual humor.
 * 4) Eddy swears with blasphemy and bathroom humor.