Yep I would take the fact it has a new battery with a pinch of salt... basically it meant he spent a couple of bucks to make the ad look better. Not that I am actually denouncing the guy or implying he is being shifty at all, as that is not my intent. I just liken advertising a new PRAM battery when selling a vintage Mac to be like advertising a 6 year old Prius and mentioning in the ad that it still has a half a tank of petrol.

Now as for Tadiran batteries, whilst Ive never seen one explode, they do seem to leak quite readily once they go flat... so whilst they wont explode in a superheated chemical reaction that instantly demolishes the surrounding area, they will still cause sometimes irreparable damage if they are left to leak after being discharged.