Lewm,
Very good question, which Fjn04 addressed nicely. Others do the same or similar for just the reason you noted, including my ex (who first discovered/gleaned/invented this use for the ME).
DIYAudio folks prefer to use a penny. Audiogoners tend to use a quarter. Private audio club members use gold doubloons. It all works!
Steady fingers, caution and good closeup vision are required for the ME-on-a-toothpick method. I have those, but for any who don't, dipping into a (stabilized) chunk of ME cleans nearly as well... and better than dipping into little vats of goo, a blob of Silly Putty or dry brushing alone.
***
Czarivey,
Nandric's cautionary post was reasonable, for the reason I explained in mine. No qualified chemist would opine that this is safe without knowing details of the chemical makeup of the cleaner, stylus glue and elastomers in the cartridge. IOW, you're just guessing.
You run an audio store. Do you recommend wet stylus cleaning to your customers? If so, do you at least warn them that this may void the warranty from some cartridge manufacturers? You owe them that information, regardless of your opinion as to its safety.