I was taught that graffiti had been most important in philology, especially studies in the development of romance languages from vulgar Latin. Classic Latin and Church Latin are rather static, whereas the graffiti on walls and Roman baths throughout the Empire show how modern languages developed.
The curses, “dirty words” and misspellings can show how people really spoke. There are wall writing over 2000 years old which translate “Caesar sucks”.
Quite a few ancient g's have survived from the Roman era, and not just because of Vesuvius. :^) In one of the Bay of Naples towns' cat houses, someone wrote, "may I always and everywhere be as potent with women as I was here." Wonder how he did? :^)
Waaaaa cool... Thanks for sharing.