Contrary to what most people say, there actually are quite a few Chinese characters that are dialect-specific.
  • For example, I have a copy of the cantonese version of the manga "Detective Conan"- when I first started reading this comic there were some sentences that I couldn't read the whole sentence- because they were using characters that represented cantonese-only words! (A prime example would be that in cantonese there is a contracted version of what, in mandarin would be pronounced "mei you" (to not have), called "mou"; however the cantonese contraction is written with a different character, one that does not appear in mandarin.)

  • An example from Shanghainese would be "vyo" which in mandarin would be "bu yao" (to not want) however again this "vyo" is written with a different character.

  • I have a copy of a fairly big chinese dictionary (the "xiandai hanyu cidian") and, while looking through it I found that a lot of the more common dialect-only words are actually included- the aforementioned "mou" in mandarin is pronounced "mao"(third tone), and vyo is pronounced "fiao"(4th tone). However although they are in the dictionary, they are not used in mandarin, they are there as a reference for people who do not understand these dialect-specific characters.

  • Furthermore, there are a lot of different usages of characters between dialects, so that even though a person might know all the characters in a sentence individually, their usage in that situation would be incomprehensible. For example, my friends and I were speaking to some people who were not from Shanghai and someone made a comment that something was very "nan ban"- and the kids who didn't know shanghainese asked "what did you just say??? what is "nan ban"? And then someone realized what he had said was a shanghainese usage of words, not a mandarin one. Also in Shanghainese the common verb for drinking liquids and smoking cigarrettes as well as eating food is "chi" (1st tone) which in mandarin means only "to eat" (this has prompted many people to joke that "Shanghainese people eat everything" because they use the verb "to eat" for eating drinking and smoking! ^_^)

    Another example of this would be a friend of mine who is from Guangdong province. When he speaks mandarin he says some interesting stuff because he uses the cantonese usages of many words even though he is speaking mandarin.