Ages ago I drew on this pair of shoes owned by Leigh, because a) we could, and b) I'd been to asked to draw on shoes before, but only for shoe companies I wasn't keen to embellish. Leigh's No-Sweat trainers however came with all the ethics and of course were owned by Leigh, so I could draw what I wanted really and not fret about it. (Fretting could be called something of a habit of mine).
Originally just the back parts were drawn on - the faces - and I quickly discovered there's a reason commercial trainers tend to be most heavily decorated on the toes; the heels disappear under hems. I finally filled the shoes up a few months ago, with some tiny Poscas and fineliners.
After years of use they're properly done in now, ready for the tip as you can see. Surprisingly ungrubby though. I think I would do this again - drawing for the sake of it!