There are many methods of phrasing one's words that are not told in a standard grammar book, especially in oral English. If there is a book or website about this kind of myths, it would be very convenient for English learners.
Do you have any books or websites other than stackexchange to recommend?
As @Esther mentioned, colloquial speech varies quite widely even between populations in the same geographic area. For written American English, however, I can heartily recommend Garner's Modern English Usage, which contains a section on what he terms "Superstitions", of which split infinitives are one example. The section on Superstitions only takes up two pages of a dictionary-length book, but he treats other similar subjects at some length, such as elegant variation, which he pointedly renames as "Inelegant Variation".
