a famous example of "word hell:" during the reign of emperor Yongzheng (18th c), a province-level examination official, in charge of administering civil service exams, put in a question using a quote from the ancient Shijing (Poetry Classic). 維民所止. the emperor's name is雍正. notice, the first and last characters of the four character quotation, resemble the name of the emperor -- but they are without the top section, the little "hat" or "roof" to the characters. the story goes that this official's enemies used this test question as evidence to the court that he wanted Yongzheng's head chopped off!
i think the real history is more complex than that. but this example of "word hell" has become a part of the folklore around the political risks of writing characters. . .