Ned, in addition to propylene glycol being a terrific furniture polish, it apparently is a great paint remover. I haven't had this problem with my Janty Kissbox, which is only a month old now, but certainly had it with an older Health mini cig. The paint started coming off the brass atomizer shell until I finally just scraped it all off with a fingernail.
I blame this on leaking fluid. And I think leaks will cause eventual paint failure on any unit.
Battery life for me, heavily using the Kissbox over the others I own, is a half-day. I rarely let one die completely and keep one on charge most of the time.