If Soundsmith said the "cartridge" was dirty, they may not have been referring to the stylus. Cartidges tend to collect gunk everywhere, including on internal surfaces that most users cannot (and should not) clean. IOW, before you go looking for solutions, make sure you understand the problem.
That said, a Magic Eraser and Zerodust regimen, if used correctly and regularly, will keep a stylus and lower cantilever as clean as the day they were made. If yours are dirty, the flaw is more likely to be in your technique than in your tools.
P.S. Soundsmith is 100% correct about compressed air. Blasting the delicate interior wiring of a cartridge with compressed air would be a great way to make the cartridge play quietly, very quietly... forever.