Another “story” to share experiences… a fellow member of my EAA chapter was in his hanger starting a normal pre-flight.  He reached in the cockpit to turn on the master switch (for lights, flaps, etc) and the engine turned over – at which point he quickly turned it back off!  The key was not in the mag switch and it was off – but the starter/mag switch had shorted in the “start” position.  It must have done this just as it was last turned off following the prior flight, otherwise the starter would have tried to engage during the prior flight.  No additional testing was done to see if the mags were live (i.e. not grounded).  However, it is assumed they were still grounded and the mixture was leaned so it was not going to start.  But if anyone had been standing by the prop they would have got a nasty burse (or worse).

Moral of the story: always be aware when turning on the master switch – unintended things could happen.

Rick