Originally Posted by HarryT
The seller was breaking copyright law by leaving the titles on the device (and you are breaking copyright law by reading them). You should do a factory reset of the Kindle and delete them.
Well, that would depend on where he/she is and the laws of that country, and the status of the individual works stored on the device.
Since he/she doesn't have a country listed, you're a bit out of bounds playing 'Internet Lawyer', Harry.