
It's always going to be a gamble when buying something from eBay that is described as 'might' just need batteries.
I have picked some watches up that did work with new batteries and also brought some that where completely dead and others that just required a clean of the battery contacts to get them to work.
I use the seller feedback as a guide if the seller has sold or is selling lots of working watches then I steer clear as I figure that in all probability they would know how to change a battery and would be savvy enough to try batteries in order to get the maximum price and therefore crafty enough to sell as untested (or maybe just needs new batteries) if they didn't work in order to get the maximum price!
On the other hand if the seller doesn't normally sell watches the possibility exists that they genuinely can't be bothered to try batteries or they don't recognize the value of a working watch against the value of a non working watch.
Also some sellers sell consignments pieces - which are just sold as seen.
One eBay seller is selling off a large collection from the estate of a collector, and doesn't seem to want to bother to test each piece.
The untested ones sell for less - so its great when you get a working one, a bit of bummer when they turn out to be garbage, but if you do buy untested you have to accept the gamble - which to me is all part of the fun!