5 days a week, 52 weeks a year, in an area with several rainy days. Yes I do recall a vast majority of slurry getting spit out on the pavement right behind the bottom bracket, not all of it, however. Hmm, right behind the bottom bracket, then where's it go?
Nevertheless, it's likely quite pointless to try to talk someone into fenders when they're just not their style.
Here's my snow-day setup. Move the backscratcher from road bike to MTB, put the studded tire on front and let it snow, let it snow, let it snow...