Often in sefarim we find that if the number of the siman spells out something negative, such as siman 304 which has a letter value of שד, we switch it around so it no longer reads as a "bad" word. Here's an example in the Tur. Here's another and another and another.
When and where did this custom originate? Did the original Tur have this configuration, or was it modified by later printers? Can it be found in earlier books?
Furthermore, does it really serve a purpose? How would it matter if a siman reads רעה?