Snodrog is described as wearing thick horn-rimmed glasses (Pedant, 7) and an outfit made of "mauve plush" covered in moons and stars and square root signs (Pedant, 25).
He lives in a miserable excuse of a house – “made out of stolen bed slats.” He would sit in this miserable house all day long, covered from head to foot with chalk dust, working out logical problems (Pedant, 7).
Snodrog's name is derived from the backwards spelling of a former Chicago eatery, Gordon's, located at 1321 East 57th Street. What transpired here to warrant commemoration is uncertain, though there are more than a few Chicago-influences within the book.
The character's pedantic tendencies come from Bellairs's friend Donald Wilcox (1938-1991), who was researching at the University of Chicago at the same time Bellairs was in graduate school. Snodrog was modeled after Wilcox "not because he was obnoxious, nor had his brain cells winked out but because he was an erudite academic nitpicker."