Protection from leaking capacitors - store upside down?
Seems viable to me... Hopefully dead ones will be detectable upon inspection. 

Just guessing here but here may be 'some' capillary action on the leads of the cap causing corrosion or whatever with electrolyte moving up but I would think it would be restricted to the leads / pads of the cap.

Unless they start making electrolytics with 'anti-gravity' electrolytes, its only logical that the majority of the expelled liquid would be drawn down and away from the board.