A query by a commenter on Victor's post raises an issue that seems worthy of discussion here on the main page. The question is whether it is possible to distinguish written Mandarin from written Cantonese. A widely believed myth is that even forms of Chinese that are mutually incomprehensible in their spoken forms are identical in writing. This is not true. Victor's post itself points out small differences between written Taiwanese Mandarin and Mainland Mandarin. Written Cantonese can in fact be distinguished from written Mandarin.
Much of the time "written Cantonese" is "Mandarin written by a Cantonese speaker" and so can only be distinguished from native Mandarin by relatively subtle cues. However, if what is written is truly Cantonese, it is easily distinguished from Mandarin if it is of any length because some common words are not cognate and are therefore written with different characters.
For example, in Mandarin, the word meaning "he, she, it" is pronounced ta¹ and is written with the characters 他, 她, and 牠 respectively. Historically this is a single word written with a single character; the gender distinction, which is made only in writing, is a fairly recent innovation. The Cantonese word for "he,she" is keui⁵, which is not cognate to ta¹ and is written 佢. In contrast to Mandarin ta¹, keui⁵ cannot refer to inanimates. A feminine form 姖 is occasionally found, but as in Mandarin the gender distinction exists only in writing. If a text uses 佢 or 姖, you can be sure that it is in Cantonese. (Note that you cannot draw this conclusion if the text merely mentions 佢 or 姖. For example, this post is in English, not Cantonese.)
Like many myths, the myth that the many forms of Chinese are identical in writing is false but has a kernel of truth. That kernel of truth is that someone who can read one form of Chinese has a fairly easy time learning to read another. For one thing, the written form erases the numerous differences in pronunciation. For another, until fairly recently there was a more-or-less standard written form not identical to any spoken dialect. Just as Europeans who spoke various languages could communicate in Latin, so until recently all literate Chinese people could communicate in the somewhat artificial written standard. With the shift over the last century to a written language that is closer to the colloquial, the differences among dialects have increased. Even so, people whose native language is something other than Mandarin often write in what is more-or-less written Mandarin, not the written version of their own dialect. Indeed, some dialects don't really have a written form, and even those that do typically do not have characters for all of the words that are not cognate to the standard Chinese word.